Q-Chem Talk - Latest posts

SCF convergence problem in CDFT-CI calculation

@jherbert John Herbert — Fri, 20 Mar 2026 11:04:25 +0000

I usually use EML (99,590) for CDFT. XC_GRID = 000099000590.

SCF convergence problem in CDFT-CI calculation

@Lee Jonghwan Lee — Fri, 20 Mar 2026 05:28:43 +0000

Hello. I have tried to calculate the electronic coupling between dye and H2O2, which is a part of the calculation of electron transfer from dye to H2O2. I intended dye in the reactant indicating negative charge and doublet state, and that in the product in the singlet ground state. Following it, I set up the CDFT-CI input and submitted the job.

$molecule
-1 2
C     1.4416816720    0.7959958748    0.9165782125
C     0.6549513616    1.8456224180    1.3697433690
C     0.1341679657    1.7940162441    2.6631639552
C     0.4119846469    0.6782839387    3.4814762044
C     1.2086647023   -0.3761940141    3.0377320825
C     1.7153419288   -0.3010270752    1.7472391229
C    -0.6924786274    2.6895146583    3.4464287904
C    -0.8762689308    2.0760147127    4.7038575600
N    -0.2031463668    0.8575011938    4.7172065639
C    -1.2891090917    3.9243729256    3.1890846174
C    -2.0564332964    4.5224355706    4.1788598943
C    -2.2365005424    3.8930420109    5.4198920829
C    -1.6533845672    2.6647764812    5.7003719753
C    -0.1588717542   -0.0491043926    5.8059047177
C     0.3667305528    0.3543751748    7.0307890509
C     0.3848923596   -0.5290871883    8.1016500173
C    -0.0969277636   -1.8365777473    7.9710391034
C    -0.6193634645   -2.2274383480    6.7325087936
C    -0.6552276424   -1.3431320088    5.6632585179
C    -0.0353703410   -2.7679446845    9.1182257020
C     1.0283275259   -2.7861136251    9.9831059860
C     1.1016267975   -3.6423816957   11.1198744980
C     0.1179681033   -4.5356501069   11.4548256660
C    -1.0080185665   -4.5684801908   10.5648343461
C    -1.0895513327   -3.6959505431    9.4122252586
N    -2.0636967070   -5.3716819444   10.6845035762
S    -3.0672505166   -5.0322399595    9.4516760500
N    -2.2107630148   -3.8616392636    8.7109777794
C     0.2102544961   -5.4225993900   12.6366297039
C    -0.6718632593   -5.2548180123   13.7301313944
C    -0.5394923880   -6.0665398452   14.8382662684
C     0.4396511267   -7.0933270179   14.9360671452
C     1.2964679008   -7.2440128514   13.8144336398
C     1.1966591224   -6.4310848096   12.6967110554
C     2.1367802728   -6.6758256140   11.5390638942
C     0.4830603186   -7.8698185908   16.1192135429
C     1.3227886110   -8.9489107495   16.5138285945
C     2.3625975607   -9.4904527738   15.7185242581
C     1.1115761132   -9.5319815187   17.7955764763
N     3.2176157368   -9.9310025493   15.0614076432
O     0.2374556059   -9.1614716258   18.6116568436
O     1.9333940106  -10.5597952218   18.1186278392
C    -1.7336569518   -4.1834120317   13.7167745269
H     1.8518094661    0.8229330935   -0.0880101531
H     0.4484479143    2.6967777839    0.7272938573
H     1.4264190774   -1.2239285061    3.6783721711
H     2.3377557245   -1.1092429191    1.3751021418
H    -1.1577954331    4.4085470552    2.2255553424
H    -2.5262621554    5.4830481819    3.9926425011
H    -2.8465858051    4.3741717276    6.1784826548
H    -1.8013979354    2.1791674114    6.6587975738
H     0.7531961823    1.3625414871    7.1411521737
H     0.7667649480   -0.1926444998    9.0603080989
H    -1.0168865001   -3.2273831232    6.6120378516
H    -1.0790511223   -1.6498884911    4.7122652152
H     1.8666149533   -2.1213899813    9.7965951088
H     1.9783961321   -3.5716220707   11.7563479245
H    -1.2086337824   -5.9155165122   15.6828566425
H     2.0519497475   -8.0191887715   13.8199459345
H     2.8890136909   -5.8856225035   11.4407666578
H     2.6679217399   -7.6209056833   11.6790434720
H     1.6007131000   -6.7226741929   10.5850828598
H    -0.2502417118   -7.6131868376   16.8775901796
H     1.6710219891  -10.8869067404   19.0062303208
H    -2.1601563683   -4.0528498017   14.7153758319
H    -1.3306462719   -3.2175241542   13.3926766854
H    -2.5482721447   -4.4413627877   13.0325550720
O     0.1056166639  -10.2568112697   20.9919965561
H     0.1036881574   -9.7641058889   20.1124212230
O     0.9193910318  -11.3905207345   20.6369306047
H     0.2524953842  -12.0904951271   20.5393223575
$end

$rem
METHOD           = CAM-B3LYP
BASIS            = 6-31+G*
SYMMETRY         = OFF
SYM_IGNORE       = TRUE
UNRESTRICTED     = TRUE
SCF_ALGORITHM    = RCA_DIIS
SCF_CONVERGENCE  = 8
MAX_SCF_CYCLES   = 200
THRESH           = 14
CDFTCI           = TRUE
CDFTCI_PRINT     = 2
CDFT_THRESH      = 7
DFT_D            = D3_ZERO
SOLVENT_METHOD   = PCM
MEM_TOTAL        = 54000
MEM_STATIC       = 8000
$end

$cdft
1.0
1.0   1   67
1.0
1.0   1   67 S
--------------
0.0
1.0   1   67
0.0
1.0   1   67 S
$end

$pcm
THEORY             CPCM
$end

$solvent
Dielectric         78.39
$end

However, there is SCF convergence issue. Considering the explanations for CDFT in Q-Chem manual,
more dense grid (SG-2) was tested too but it provided a similar tendency. Could you give me an advice to treat this issue? Thank you for your kind comments in advance.

 -------------------------------------------------------
 OpenMP Integral computing Module                
 -------------------------------------------------------
 Inaccurate integrated density:
   Number of electrons =   319
   Numerical integral  =   318.001540443914
   Relative error      =    -0.3129967260 %
 Inaccurate integrated density:
   Number of electrons =   319
   Numerical integral  =   318.001540443914
   Relative error      =    -0.3129967260 %
 ---------------------------------------
  Cycle       Energy         DIIS Error
 ---------------------------------------
    1   -2317.9681264161      3.99E-02
    2   -2304.1562028547      4.10E-03
    3   -2304.1624574616      4.05E-03
    4   -2304.1684607752      3.99E-03
    5   -2304.1742291191      3.94E-03
    6   -2304.1797774117      3.89E-03
    7   -2304.1851193036      3.85E-03
    8   -2304.1902673161      3.80E-03
    9   -2304.1952329575      3.75E-03
   10   -2304.2000268155      3.71E-03
   11   -2304.2046586592      3.67E-03
   12   -2304.2091375087      3.63E-03
   13   -2304.2134717110      3.59E-03
   14   -2304.2176689984      3.55E-03
   15   -2304.2217365498      3.51E-03
   16   -2304.2256810346      3.47E-03
   17   -2304.2295086572      3.44E-03
   18   -2304.2332251966      3.40E-03
   19   -2304.2368360540      3.37E-03
   20   -2304.2403462682      3.34E-03
   21   -2304.2437605515      3.30E-03
   22   -2304.2470833208      3.27E-03
   23   -2304.2503187139      3.24E-03
   24   -2304.2534706123      3.21E-03
   25   -2304.2565426640      3.18E-03
   26   -2304.2595383001      3.15E-03
   27   -2304.2624607526      3.13E-03
   28   -2304.2653130655      3.10E-03
   29   -2304.2680981051      3.07E-03
   30   -2304.2708185816      3.05E-03
   31   -2304.2734770577      3.02E-03
   32   -2304.2760759510      3.00E-03
   33   -2304.2786175563      2.97E-03
   34   -2304.2811040422      2.95E-03
   35   -2304.2835374670      2.92E-03
   36   -2304.2859197804      2.90E-03
   37   -2304.2882528382      2.88E-03
   38   -2304.2905383965      2.86E-03
   39   -2304.2927781399      2.83E-03
   40   -2304.2949736505      2.81E-03
   41   -2304.2971264505      2.79E-03
   42   -2304.2992379858      2.77E-03
   43   -2304.3013096348      2.75E-03
   44   -2304.3033427149      2.73E-03
   45   -2304.3053384812      2.71E-03
   46   -2304.3072981398      2.69E-03
   47   -2304.3092228437      2.67E-03
   48   -2304.3111137056      2.66E-03
   49   -2304.3129718047      2.64E-03
   50   -2304.3147982235      2.62E-03 Done RCA. Switching to DIIS
   51   -2280.6368036369      3.19E-03
   52  -38048.6543268810      1.01E+00
   53  -38466.4650297180      9.85E-01
   54  -38544.5632716962      9.79E-01
   55  -37804.8943324800      1.02E+00
   56  -37821.2989438169      1.02E+00
   57  -37092.3396863271      1.05E+00
   58  -37215.7874075679      1.05E+00
   59  -37213.2948842934      1.05E+00
   60  -37260.3352907686      1.04E+00
   61  -37277.4668534616      1.04E+00
   62  -37177.2022308505      1.04E+00
   63  -37074.6163068897      1.05E+00
   64  -37043.9550593695      1.05E+00
   65  -37079.8979418483      1.05E+00
   66  -41060.7953250748      4.70E-01
 Inaccurate integrated density:
   Number of electrons =   319
   Numerical integral  =   319.042579677649
   Relative error      =     0.0133478613 %
   67  -48563.1835958344      2.77E-01
 Inaccurate integrated density:
   Number of electrons =   319
   Numerical integral  =   319.057854015960
   Relative error      =     0.0181360552 %
   68  -48783.8442430928      1.45E-01
   69  -45907.9865531915      1.30E-01
 Inaccurate integrated density:
   Number of electrons =   319
   Numerical integral  =   319.062246987649
   Relative error      =     0.0195131623 %
   70  -46649.5494287290      9.21E-02
   71  -47722.8543121855      6.94E-02
 Inaccurate integrated density:
   Number of electrons =   319
   Numerical integral  =   319.041289008109
   Relative error      =     0.0129432627 %
   72  -48390.0311882042      5.33E-02
   73  -48150.7236732649      6.09E-02
 Inaccurate integrated density:
   Number of electrons =   319
   Numerical integral  =   319.035433846978
   Relative error      =     0.0111077890 %
   74  -48856.3541936928      5.57E-02
   75  -48647.8243775495      4.79E-02
   76  -49192.3983285075      2.47E-02
   77  -48967.5938841930      3.66E-02
   78  -49149.2807739707      1.60E-02
   79  -49173.0530873448      2.09E-02
   80  -49165.7375795098      1.24E-02
   81  -49246.0468272284      1.23E-02
   82  -49208.8705458530      6.19E-03
   83  -49203.8611726063      1.07E-02
   84  -49225.2601352762      4.70E-03
   85  -49223.6564311864      4.13E-03
   86  -49206.0280936272      6.90E-03
   87  -49223.4972156756      1.65E-03
   88  -49227.1056970573      1.26E-03
   89  -49224.0508810993      1.02E-03
   90  -49225.9655010744      7.97E-04
   91  -49225.7813041486      6.65E-04
   92  -49225.4981806053      6.45E-04
   93  -49225.2955719740      5.42E-04
   94  -49225.1246122827      4.52E-04
   95  -49224.7896288044      3.14E-04
   96  -49224.7757962654      1.99E-04
   97  -49224.6964264745      1.38E-04
   98  -49224.6802569561      1.09E-04
   99  -49224.6977355697      8.31E-05
  100  -49224.7035894015      7.19E-05
  101  -49224.7592810717      5.96E-05
  102  -49224.7731142717      5.43E-05
  103  -49224.7813722824      4.85E-05
  104  -49224.7738797404      4.68E-05
  105  -49229.4034234842      3.09E-04
  106  -49229.4038739041      3.09E-04
  107  -49229.4015388505      3.08E-04
  108  -49229.4128926071      3.09E-04
  109  -49229.4204501648      3.07E-04
  110  -49229.4182099293      3.05E-04
  111  -49229.4209402145      3.05E-04
  112  -49229.4139431345      3.04E-04
  113  -49229.4235315577      3.03E-04
  114  -49229.4299559001      3.01E-04
  115  -49229.4394202175      3.04E-04
  116  -49229.4366788807      3.03E-04
  117  -49229.4046159521      3.04E-04
  118  -49229.4033316897      2.98E-04
  119  -49229.3984023484      2.99E-04
  120  -49229.8188918839      9.93E-04
  121  -49229.8293553535      8.09E-04
  122  -49229.8707616226      3.78E-04
  123  -49229.8631798032      2.60E-04
  124  -49229.8863001613      4.93E-05
  125  -49229.8940981754      3.20E-05
  126  -49229.8856063916      2.61E-05
  127  -49229.8832375062      2.87E-05
  128  -49229.8866487348      2.94E-05
  129  -49229.8953451985      2.21E-05
  130  -49229.9019043575      2.20E-05
  131  -49229.9081149329      1.57E-05
  132  -49229.9120011560      1.27E-05
  133  -49229.9154360210      9.98E-06
  134  -49229.9209618684      8.74E-06
  135  -49228.7591915849      3.70E-04
  136  -49228.7587355591      3.70E-04
  137  -49228.7587058713      3.70E-04
  138  -49228.7588568942      3.71E-04
  139  -49228.7599916302      3.76E-04
  140  -49228.7585467970      3.73E-04
  141  -49228.7590210581      3.65E-04
  142  -49228.7568286464      3.47E-04
  143  -49228.7542602760      3.20E-04
  144  -49228.7584330301      3.49E-04
  145  -49228.7544113971      3.22E-04
  146  -49228.7532995613      3.17E-04
  147  -49228.7550947012      3.24E-04
  148  -49228.7547238870      3.24E-04
  149  -49228.7520617104      3.10E-04
  150  -49228.4044204250      4.51E-04
  151  -49228.4043413000      4.51E-04
  152  -49228.4042854731      4.52E-04
  153  -49228.4041245249      4.52E-04
  154  -49228.4031091019      4.53E-04
  155  -49228.4012276966      4.55E-04
  156  -49228.3977942420      4.59E-04
  157  -49228.3948245447      4.63E-04
  158  -49228.3915185936      4.66E-04
  159  -49228.4116321265      4.39E-04
  160  -49228.4512080296      2.03E-04
  161  -49228.4427037424      5.19E-05
  162  -49228.4550860027      7.63E-05
  163  -49228.4501322927      1.63E-05
  164  -49228.4522850111      9.19E-06
  165  -49227.2185538749      2.92E-04
  166  -49227.2185461154      2.91E-04
  167  -49227.2184028683      2.91E-04
  168  -49227.2217793188      3.02E-04
  169  -49227.2121225110      2.49E-04
  170  -49227.2022635888      2.14E-04
  171  -49227.2007699111      2.09E-04

NAC calculation

@jherbert John Herbert — Wed, 18 Mar 2026 14:43:55 +0000

Probably meta-GGAs at that time. I believe this is implemented in more recent versions of Q-Chem.

NAC calculation

@leonardo00 Leonardo Rotondi — Wed, 18 Mar 2026 12:19:21 +0000

Hi,

I’m using QChem 6.2 to compute NAC between several states. I’m using the following input:

$molecule
1 2
Fe 0.85765499690809 5.84486188593330 9.80779695138497
N 3.37766610488645 4.46231262779497 10.37972775042476
N 3.30438506334604 4.73297366817512 8.23745685763065
N -0.56650501101824 3.58575944307604 11.43599308415345
N 1.51317842633565 3.86849934652993 11.95746752469392
N 2.65497380146161 6.03555981656861 12.18938783040008
N 1.74077513105160 7.97253231065819 11.89734610150523
C 4.10637582036955 2.44267249684139 12.96108620636726
H 3.29918433839942 1.82678159007433 12.58170253644286
C 4.07732357454341 3.83160633326596 12.76437577959528
C 0.54329433892223 4.29664268838383 11.11279069555879
C 1.83468386732130 6.72838304023850 11.36142763728778
C 4.48372407237940 4.06696552365724 8.51501696394748
H 5.17366213121274 3.77818368143032 7.74018725908446
C 2.62270629096449 4.98134759159911 9.38491174009016
C 6.27237482604986 3.92682623798256 13.83861066938144
H 7.12390837183097 4.51676463645511 14.16014015583139
C 5.20404014025043 4.54750440607471 13.19632003664982
H 5.27233093934609 5.61232129077263 13.00594932473295
C -0.30769462384421 2.75130382577036 12.50518190893631
H -1.06174064870868 2.10767933759428 12.92570913640153
C 5.16796771129012 1.80923759220848 13.60226315208484
H 5.15063504449411 0.73322169685140 13.73796423849384
C 1.00922991329186 9.10099576079398 11.34012283796301
H 0.51011659972377 8.77325158557209 10.43390846540519
H 0.27063928173222 9.45623587181180 12.05974581972226
H 1.70316453730426 9.90921014712331 11.10466221960912
C 0.99544291782402 2.94011694945383 12.83524881596451
H 1.57452656865483 2.49658256861049 13.62481227156574
C 4.52444560362943 3.89811277300130 9.86072574648058
H 5.26737873605908 3.42644635784244 10.47937060470780
C 3.02373083668401 6.82666854925167 13.26109071946610
H 3.63595076979174 6.46770504497603 14.06835861671851
C 2.46322708758544 8.04614058160777 13.07568833195789
H 2.51110842651362 8.94799432105845 13.66223479536240
C 2.88416389970133 5.08710715098333 6.88891760128461
H 1.93464130268280 5.60849597933397 6.94889547139380
H 2.76963792204817 4.18316034449893 6.28955144336766
H 3.63083136533566 5.73463458020935 6.42806032476040
C -1.85993995878052 3.65864812178874 10.77087097258982
H -2.62148919737756 3.99816681812314 11.47388307201583
H -1.77944940297992 4.35944996111920 9.94632482883975
H -2.12999092010489 2.67189969659366 10.39307358680806
C 6.25330743226439 2.55252271997366 14.05637387118082
H 7.08161974706133 2.06449149105611 14.55786046168541
B 2.93449398793973 4.53003938061650 11.88315488553251
N -1.66236767499486 7.22739137794060 9.23589972120795
N -1.58920984695971 6.95645737247723 11.37815543159556
N 2.28179494713700 8.10409620689366 8.17977280683494
N 0.20214456706151 7.82131387273459 7.65819632805559
N -0.93967219050864 5.65428203339255 7.42618601377251
N -0.02512312392805 3.71742199473050 7.71782431725011
C -2.39193664437502 9.24707576322246 6.65532484593229
H -1.58535942000317 9.86331011893101 7.03543317264928
C -2.36205074351781 7.85805562656983 6.85131348004497
C 1.17201282851586 7.39314116629795 8.50287516840847
C -0.11932757017490 4.96141414691051 8.25406506601535
C -2.76845696477635 7.62263336243869 11.10061222898242
H -3.45843521946601 7.91131518392128 11.87544706730581
C -0.90741707255880 6.70831563210161 10.23070893107869
C -4.55662466203449 7.76193874319747 5.77619527323548
H -5.40763542895409 7.17160994844402 5.45400575791864
C -3.48811101049235 7.14162836660203 6.41855214407614
H -3.55569115660301 6.07663029643272 6.60823919934222
C 2.02304390731017 8.93851888032441 7.11054998446713
H 2.77710039452801 9.58214674912260 6.69005226567926
C -3.45374103882823 9.88015208254474 6.01413773494993
H -3.43710000455284 10.95625756816903 5.87906763510980
C 0.70704668919162 2.58912741213440 8.27456376499319
H 1.20621893514267 2.91685967195599 9.18075858070179
H 1.44564613714049 2.23440359425149 7.55469036543272
H 0.01352041106189 1.78054293247447 8.50997552783401
C 0.71994914371123 8.74961820632832 6.78036150888961
H 0.14094123631725 9.19306202122124 5.99068937575465
C -2.80912383287320 7.79162708151601 9.75491695742473
H -3.55202621873467 8.26336273584637 9.13628778181042
C -1.30868508895647 4.86320179704661 6.35455589487087
H -1.92116501667552 5.22215801759484 5.54747817325010
C -0.74789003345844 3.64381579393745 6.53966186711113
H -0.79568508330733 2.74205091186346 5.95296351965923
C -1.16924804959390 6.60195278650913 12.72668762084997
H -0.21983997800646 6.08035384298268 12.66677469850773
H -1.05460632716130 7.50574089655907 13.32627000639324
H -1.91614169521414 5.95451295563637 13.18728708241275
C 3.57514704114351 8.03134657144642 8.84506425189604
H 4.33681865224376 7.69188168941808 8.14217192396274
H 3.49463387137489 7.33056772355243 9.66962741648354
H 3.84505048987037 9.01813350698010 9.22286294917773
C -4.53840661823213 9.13638239970090 5.55920542563089
H -5.36686180470840 9.62412670315899 5.05768088712423
B -1.21915589647714 7.15976543114950 7.73249154045499
$end

$rem
METHOD = TPSSh
BASIS = def2-TZVP
SCF_CONVERGENCE = 6
SYM_IGNORE = true
SOLVENT_METHOD pcm
MEM_TOTAL 200000
MEM_STATIC 1000
SET_ITER 300
MAX_SCF_CYCLES 200
MAX_CIS_CYCLES 200
GUI = 2
CIS_N_ROOTS = 7
CALC_NAC = true
CIS_DER_NUMSTATE = 8
$end

$derivative_coupling
NACME for IC between GS and ESs
0 1 2 3 4 5 6 7
$end

$pcm
Theory CPCM
Method SWIG
Solver Inversion
Radii Read
SurfaceType VDW_SAS
SASradius 1.3
HeavyPoints 110
$end

$solvent
Dielectric 9.08
OpticalDielectric 2.0282
$end

$van_der_waals
1
26 2.40
$end

which led to the following error as the derivative couplings part started:

         CIS Derivative Couplings

          between states 0 and 1

NCharge is 0
get_w_dc time: CPU 8191.47 s wall 701.44 s
AOints 129 time: CPU 69795.45 s wall 5928.58 s

Q-Chem fatal error occurred in module libdftn/xcfunc.C, line 2683:

No 3rd derivatives for TPSS!

Please submit a crash report at Q-Chem Crash Reporter

Are there functionals for which NACME is not implemented? Which are they?

Leonardo

Strange outcome in RAS-SF calculation

@Lee Jonghwan Lee — Tue, 17 Mar 2026 19:00:27 +0000

Hello. I have been trying to perform RAS-3SF-CI calculations for three fragments. Here is my input file.

$molecule
0 1
H	-10.8887670836	9.0153038910	0.7969064427
C	-4.9758426863	1.6872893090	1.2587267125
C	-4.1641961905	0.8368007247	1.5509277189
C	-8.9785626763	5.4422860852	-0.1938275405
C	-9.8547538915	6.2202825250	-0.5157271136
Si	-11.2178163665	7.3428735526	-1.0224652683
C	-12.6619174443	6.2841484653	-1.5913878968
C	-11.7217846743	8.3978226569	0.4471530327
C	-10.6105280980	8.4298878840	-2.4282610597
C	-5.9652468038	2.6390861320	0.9066286120
C	-7.9695239711	4.5122110550	0.1803689036
C	-6.6109891049	4.8083856138	-0.0733487311
C	-5.5927822820	3.8590381501	0.2956106229
C	-7.3275783673	2.3331900320	1.1444490553
C	-8.3436114348	3.2858847852	0.7767220134
C	-7.7262233926	1.1062429845	1.7116650802
C	-9.0549149366	0.7912531477	1.9163234920
C	-10.0710795947	1.7460390163	1.5510989043
C	-9.6956957006	2.9555932064	1.0022833972
C	-9.4640591317	-0.4665045375	2.4741202983
C	-11.4477071158	1.3975285800	1.7623515044
C	-11.7879714363	0.1958864196	2.2912190210
C	-10.7774981617	-0.7536252058	2.6537118341
C	-4.2473653214	4.1654459189	0.0152295776
C	-3.8827259767	5.3405935683	-0.6109366104
C	-4.9022726907	6.2908786732	-0.9806182004
C	-6.2239221089	6.0081861256	-0.7018986158
C	-4.5060459790	7.5025151381	-1.6391752496
C	-3.2010670811	7.7506484081	-1.9120149565
C	-2.1875639770	6.8061386029	-1.5446493231
C	-2.5157663910	5.6488071232	-0.9182400932
H	-12.3803012350	5.6591154803	-2.4442445270
H	-13.5079344637	6.9093058673	-1.8971547637
H	-13.0072331277	5.6224002589	-0.7907862550
H	-12.0540238897	7.7781563855	1.2857268520
H	-12.5461232604	9.0666727722	0.1764035984
H	-11.4014535103	9.1118799082	-2.7587784166
H	-10.3032570857	7.8288426574	-3.2896338849
H	-9.7532727059	9.0356475205	-2.1185479022
H	-6.9645542156	0.3829619912	1.9819402681
H	-10.4594117663	3.6727568540	0.7208651656
H	-8.6949513434	-1.1841215060	2.7452847815
H	-11.0761044368	-1.7091896208	3.0733995572
H	-3.4826670570	3.4468081291	0.2912709122
H	-6.9959365271	6.7173279965	-0.9817384640
H	-5.2803180229	8.2122235996	-1.9163125452
H	-2.9119125880	8.6688280267	-2.4133996011
H	-1.1502074134	7.0277596916	-1.7748462731
H	-1.7515434461	4.9290632484	-0.6390466089
H	-12.2102174687	2.1192279523	1.4833427371
H	-12.8321493135	-0.0588980262	2.4437113889
S	-1.8380369623	-3.8863482076	3.3505300178
C	-2.3964743720	-2.3429218117	2.7636279329
C	-1.4573889835	-1.6268534175	2.0458065663
S	-3.9232209039	-1.5525526500	2.8578775119
C	-3.2946560308	-0.2148075895	1.8962769868
C	-1.9821535983	-0.3996240826	1.5537251464
H	-1.4317466000	0.3130971006	0.9533275484
C	-0.2973996232	-3.5691888743	2.6003675156
C	-0.2174554761	-2.3525087941	1.9501047014
S	1.1506446484	-4.4945614107	2.4863186772
C	1.8994462709	-3.2112851989	1.5375695984
C	1.0495311509	-2.1561910263	1.3394659498
H	1.3324630131	-1.2792050660	0.7721134455
Si	12.6500780793	-3.9435463300	-2.0133354263
C	13.0494337937	-2.2936009641	-2.8182217055
C	13.7761620594	-4.2388531937	-0.5397176080
C	12.8202349650	-5.3376323117	-3.2599184611
H	12.9380154643	-1.4702794844	-2.1054928395
H	12.3851730184	-2.0967057672	-3.6654475126
H	14.0801737607	-2.2788698588	-3.1888711039
H	13.6877952636	-3.4290999358	0.1909066429
H	14.8230730693	-4.2938232176	-0.8575504975
H	13.5294463103	-5.1762977794	-0.0319389221
H	12.5736536924	-6.3048531545	-2.8110936699
H	13.8464100079	-5.3955001807	-3.6390088732
H	12.1540671766	-5.1859353313	-4.1146072192
C	3.2303482104	-3.3374424233	1.0979837925
C	4.3800289205	-3.4309003572	0.7279228783
C	5.7245928098	-3.5227412479	0.2888075897
C	6.3553369178	-2.3870361245	-0.2723594892
C	7.7195075577	-2.4819720260	-0.7243077719
C	8.4127424417	-3.7086823690	-0.5991473495
C	7.7777323749	-4.8468743760	-0.0510680700
C	6.4130208143	-4.7533350138	0.3994069909
C	5.7902425759	-5.9035558260	0.9228722738
C	6.4462973995	-7.1148976517	1.0083810109
C	7.8127717942	-7.2096258100	0.5587669364
C	8.4384875385	-6.0881753655	0.0517983546
C	5.8081032912	-8.2933932424	1.5224254057
C	8.4749506840	-8.4804477665	0.6465305132
C	7.8316045027	-9.5687505496	1.1378335603
C	6.4730126746	-9.4738298451	1.5841300486
C	5.6755288397	-1.1628741380	-0.4192035494
C	6.2746918657	-0.0596543823	-0.9923297175
C	7.6393991276	-0.1537484073	-1.4468118036
C	8.3218085498	-1.3448825572	-1.2988320375
C	5.5781359116	1.1829901100	-1.1617146279
C	6.1868800708	2.2482228785	-1.7395081488
C	7.5435496523	2.1553125790	-2.1918722393
C	8.2413293929	1.0009207007	-2.0495102193
C	9.7589315936	-3.8035736313	-1.0464329870
C	10.9099317254	-3.8808270113	-1.4281233841
H	4.7594906403	-5.8337569637	1.2547012176
H	9.4654033314	-6.1596177823	-0.2903932402
H	4.7772738318	-8.2165385958	1.8566710254
H	9.5041283904	-8.5493074866	0.3059511473
H	8.3416574934	-10.5251929157	1.1964886116
H	5.9800687684	-10.3597933913	1.9720407980
H	4.6468166294	-1.0954026034	-0.0809917665
H	9.3480973117	-1.4208240230	-1.6421037382
H	4.5491091690	1.2462676907	-0.8188883132
H	5.6495941982	3.1829562642	-1.8657249943
H	8.0080219610	3.0217163920	-2.6520684592
H	9.2693747924	0.9242685889	-2.3917462340
$end

$rem
JOBTYPE = SP
EXCHANGE = HF
BASIS = 6-31G*
UNRESTRICTED = FALSE
SYM_IGNORE = TRUE
SYMMETRY = FALSE
SCF_ALGORITHM = DIIS
MAX_SCF_CYCLES = 512
SCF_CONVERGENCE = 8
THRESH = 14
MEM_TOTAL = 96000
MEM_STATIC = 16000
$end

@@@

$molecule
0 7
read
$end

$rem
JOBTYPE = SP
EXCHANGE = HF
CORRELATION = RASCI
BASIS = 6-31G*
UNRESTRICTED = FALSE
SCF_ALGORITHM = DIIS
MAX_SCF_CYCLES = 512
SCF_CONVERGENCE = 8
THRESH = 14
SCF_GUESS = READ
MEM_TOTAL = 96000
MEM_STATIC = 16000

RAS_ACT = 6
RAS_ELEC = 6
RAS_OCC = 255
RAS_ROOTS = 10
RAS_SPIN_MULT = 1
RAS_NFRAG = 3
RAS_NFRAG_ATOMS = [51,13,51]
RAS_PRINT = 3
RAS_AMPL_PRINT = 10
SET_ITER = 512
$end

After completing the calculation, the outcome looks strange as all states are printed as charge-resonance state. The suspected reason why the issue occurred is assigning the active orbitals (RAS2) to fragments wrongly. You can confirm the relevant parts below. I conducted RAS-SF calculations for various molecules, and there are very rare events like it.

How can I resolve this issue? Your kind and insightful comments would surely be helpful for me. Thank you in advance.

     ##========================================##
     ||                                        ||
     ||              R A S M A N 2             ||
     ||________________________________________||
     ||                                        ||
     ||  Author:                               ||
     ||                                        ||
     ||        David Casanova (2010)           ||
     ||                                        ||
     ##========================================##
  
  ***************************************************
  *  RAS-CI Dimensions:                             *
  *                                                 *
  *  Active Elec.:   6           Active Orb.:   6   *
  *  Doubly Occ. : 255           Doubly Vir.: 912   *
  *  Frozen Occ. :   0           Frozen Vir.:   0   *
  *                                                 *
  *  Total CI configurations:    700600             * 
  *    Active configurations:       400             * 
  *      Hole configurations:    153000             * 
  *  Particle configurations:    547200             * 
  *                                                 *
  *   Requested states:       10                    *
  *  Spin multiplicity: Singlets                    *
  *                                                 *
  ***************************************************
 Each CI-vector requires      5.34515 MB 
 Max. subspace vectors           5120      
  
Building fragment localized orbitals
Localization of MOs in   3 fragments
Basis functions in Fragment  1:    1 -   496
Basis functions in Fragment  2:  497 -   677
Basis functions in Fragment  3:  678 -  1173
RAS1,RAS2 and RAS3 MOs will be localized separatelly
Localizing orbitals     1 -   255
Localizing orbitals   256 -   261
Localizing orbitals   262 -  1173
Building Zero-order Fock matrix
RAS1 HF-like energy:          -4292.1404570109
Reordering Fragment MOs by energy
Computing integrals
Computing J and K matrices
Computing addressing
Making amplitude guesses
   3 guesses with   0 unpaired electrons
   5 guesses with   2 unpaired electrons
   2 guesses with   4 unpaired electrons
Direct CI diagonalization
 ---------------------------------------------------
 Iter    Rts Conv    Rts Left    Ttl Dev     Max Dev
 ---------------------------------------------------
   1         0          10      0.004230    0.000499
   2         0          10      0.003428    0.000552
   3         0          10      0.004503    0.000709
   4         0          10      0.004319    0.000919
   5         0          10      0.005627    0.001293
   6         0          10      0.005990    0.000949
   7         0          10      0.004642    0.000701
   8         0          10      0.004577    0.000651
   9         0          10      0.003907    0.000663
  10         0          10      0.004158    0.000669
  11         0          10      0.004428    0.000880
  12         0          10      0.003836    0.000832
  13         0          10      0.003409    0.000727
  14         0          10      0.003400    0.000693
  15         0          10      0.003516    0.000632
  16         0          10      0.002873    0.000655
  17         0          10      0.002765    0.000519
  18         0          10      0.002464    0.000480
  19         0          10      0.002242    0.000431
  20         0          10      0.002183    0.000403
  21         0          10      0.002071    0.000451
  22         0          10      0.001856    0.000404
  23         0          10      0.002137    0.000567
  24         0          10      0.002187    0.000575
  25         0          10      0.001857    0.000458
  26         0          10      0.001840    0.000557
  27         0          10      0.001684    0.000440
  28         0          10      0.001483    0.000412
  29         0          10      0.001368    0.000358
  30         0          10      0.001728    0.000426
  31         0          10      0.001652    0.000426
  32         0          10      0.001501    0.000406
  33         0          10      0.001778    0.000434
  34         0          10      0.002940    0.000752
  35         0          10      0.002962    0.000738
  36         0          10      0.002607    0.000672
  37         0          10      0.002350    0.000606
  38         0          10      0.002026    0.000413
  39         0          10      0.001962    0.000398
  40         0          10      0.001701    0.000327
  41         0          10      0.001711    0.000414
  42         0          10      0.001486    0.000347
  43         0          10      0.001396    0.000349
  44         0          10      0.001327    0.000325
  45         0          10      0.001267    0.000309
  46         1           9      0.001156    0.000238
  47         1           9      0.001049    0.000259
  48         1           9      0.000984    0.000279
  49         1           9      0.000860    0.000247
  50         1           9      0.000780    0.000226
  51         1           9      0.000735    0.000207
  52         1           9      0.000645    0.000175
  53         1           9      0.000606    0.000155
  54         1           9      0.000565    0.000141
  55         1           9      0.000516    0.000132
  56         1           9      0.000459    0.000127
  57         1           9      0.000411    0.000130
  58         1           9      0.000397    0.000137
  59         1           9      0.000336    0.000127
  60         1           9      0.000313    0.000122
  61         1           9      0.000275    0.000109
  62         1           9      0.000221    0.000088
  63         1           9      0.000206    0.000086
  64         1           9      0.000199    0.000083
  65         1           9      0.000159    0.000066
  66         1           9      0.000144    0.000064
  67         1           9      0.000124    0.000056
  68         1           9      0.000106    0.000045
  69         1           9      0.000097    0.000045
  70         2           8      0.000084    0.000039
  71         2           8      0.000071    0.000033
  72         2           8      0.000065    0.000031
  73         2           8      0.000057    0.000026
  74         2           8      0.000052    0.000024
  75         2           8      0.000046    0.000023
  76         2           8      0.000040    0.000020
  77         3           7      0.000037    0.000017
  78         3           7      0.000033    0.000016
  79         3           7      0.000030    0.000015
  80         3           7      0.000028    0.000014
  81         3           7      0.000024    0.000012
  82         5           5      0.000022    0.000011
  83         5           5      0.000021    0.000010
  84         5           5      0.000018    0.000009
  85         6           4      0.000017    0.000008
  86         6           4      0.000016    0.000008
  87         7           3      0.000015    0.000007
  88         8           2      0.000014    0.000007
  89         8           2      0.000014    0.000007
  90         8           2      0.000013    0.000006
  91         8           2      0.000013    0.000007
  92         9           1      0.000013    0.000007
  93         9           1      0.000013    0.000006
  94         9           1      0.000013    0.000007
  95         9           1      0.000013    0.000007
  96         9           1      0.000013    0.000007
  97         9           1      0.000015    0.000009
  98         9           1      0.000016    0.000010
  99         9           1      0.000016    0.000010
 100         9           1      0.000020    0.000014
 101         9           1      0.000021    0.000015
 102         9           1      0.000026    0.000020
 103         9           1      0.000037    0.000031
 104         9           1      0.000050    0.000044
 105         9           1      0.000104    0.000098
 106         9           1      0.000132    0.000126
 107         9           1      0.000119    0.000113
 108         8           2      0.000129    0.000121
 109         8           2      0.000113    0.000105
 110         8           2      0.000104    0.000097
 111         9           1      0.000105    0.000099
 112         9           1      0.000086    0.000080
 113         9           1      0.000085    0.000079
 114         9           1      0.000086    0.000080
 115         9           1      0.000069    0.000064
 116         9           1      0.000071    0.000065
 117         9           1      0.000065    0.000060
 118         9           1      0.000058    0.000052
 119         9           1      0.000063    0.000057
 120         9           1      0.000049    0.000043
 121         9           1      0.000046    0.000040
 122         9           1      0.000050    0.000044
 123         9           1      0.000040    0.000035
 124         9           1      0.000041    0.000035
 125         9           1      0.000040    0.000034
 126         9           1      0.000034    0.000028
 127         9           1      0.000036    0.000030
 128         9           1      0.000031    0.000025
 129         9           1      0.000029    0.000023
 130         9           1      0.000030    0.000024
 131         9           1      0.000025    0.000019
 132         9           1      0.000027    0.000021
 133         9           1      0.000025    0.000019
 134         9           1      0.000021    0.000016
 135         9           1      0.000023    0.000017
 136         9           1      0.000021    0.000015
 137         9           1      0.000020    0.000014
 138         9           1      0.000020    0.000014
 139         9           1      0.000018    0.000012
 140         9           1      0.000018    0.000013
 141         9           1      0.000018    0.000012
 142         9           1      0.000016    0.000010
 143         9           1      0.000016    0.000010
 144         9           1      0.000015    0.000010
 145         9           1      0.000015    0.000009
 146         9           1      0.000015    0.000009
 147         9           1      0.000013    0.000008
 148         9           1      0.000014    0.000008
 149         9           1      0.000013    0.000008
 150         9           1      0.000012    0.000007
 151         9           1      0.000013    0.000007
 152         9           1      0.000012    0.000006
 153         9           1      0.000011    0.000005
 154         9           1      0.000012    0.000006
 155         9           1      0.000011    0.000006
 156         9           1      0.000011    0.000005
 157         9           1      0.000012    0.000006
 158         9           1      0.000011    0.000005
 159         9           1      0.000011    0.000005
 160         9           1      0.000011    0.000005
 161         9           1      0.000010    0.000004
 162         9           1      0.000011    0.000005
 163         9           1      0.000010    0.000005
 164         9           1      0.000010    0.000004
 165         9           1      0.000010    0.000005
 166         9           1      0.000010    0.000004
 167         9           1      0.000010    0.000004
 168         9           1      0.000010    0.000004
 169         9           1      0.000010    0.000004
 170         9           1      0.000010    0.000004
 171         9           1      0.000010    0.000004
 172         9           1      0.000010    0.000004
 173         9           1      0.000010    0.000004
 174         9           1      0.000010    0.000005
 175         9           1      0.000011    0.000005
 176         9           1      0.000011    0.000006
 177         9           1      0.000012    0.000006
 178         9           1      0.000014    0.000008
 179         9           1      0.000017    0.000012
 180         8           2      0.000037    0.000028
 181         8           2      0.000448    0.000349
 182         8           2      0.000493    0.000471
 183         6           4      0.000675    0.000641
 184         8           2      0.000615    0.000602
 185         8           2      0.000573    0.000562
 186         8           2      0.000607    0.000596
 187         7           3      0.000491    0.000481
 188         8           2      0.000449    0.000439
 189         8           2      0.000411    0.000400
 190         8           2      0.000306    0.000296
 191         8           2      0.000292    0.000282
 192         8           2      0.000237    0.000226
 193         8           2      0.000213    0.000201
 194         8           2      0.000177    0.000165
 195         8           2      0.000132    0.000120
 196         8           2      0.000137    0.000123
 197         8           2      0.000132    0.000115
 198         8           2      0.000114    0.000091
 199         8           2      0.000135    0.000092
 200         8           2      0.000258    0.000177
 201         8           2      0.000305    0.000233
 202         8           2      0.000424    0.000350
 203         7           3      0.000585    0.000518
 204         7           3      0.000658    0.000595
 205         6           4      0.000683    0.000611
 206         8           2      0.000631    0.000565
 207         8           2      0.000578    0.000515
 208         8           2      0.000553    0.000479
 209         7           3      0.000882    0.000451
 210         7           3      0.000848    0.000445
 211         7           3      0.000765    0.000412
 212         7           3      0.000672    0.000358
 213         7           3      0.000621    0.000319
 214         7           3      0.000550    0.000311
 215         7           3      0.000451    0.000219
 216         7           3      0.000434    0.000214
 217         7           3      0.000401    0.000207
 218         7           3      0.000360    0.000157
 219         7           3      0.000331    0.000155
 220         7           3      0.000306    0.000127
 221         7           3      0.000290    0.000113
 222         7           3      0.000258    0.000105
 223         6           4      0.000756    0.000512
 224         6           4      0.000657    0.000437
 225         6           4      0.000623    0.000400
 226         6           4      0.000492    0.000311
 227         6           4      0.000470    0.000292
 228         6           4      0.000421    0.000260
 229         6           4      0.000278    0.000171
 230         6           4      0.000275    0.000166
 231         6           4      0.000243    0.000146
 232         6           4      0.000196    0.000120
 233         6           4      0.000174    0.000105
 234         6           4      0.000147    0.000089
 235         6           4      0.000143    0.000087
 236         6           4      0.000117    0.000071
 237         6           4      0.000093    0.000057
 238         6           4      0.000099    0.000062
 239         6           4      0.000081    0.000049
 240         6           4      0.000069    0.000043
 241         6           4      0.000068    0.000043
 242         6           4      0.000056    0.000034
 243         6           4      0.000054    0.000034
 244         6           4      0.000048    0.000030
 245         6           4      0.000038    0.000024
 246         6           4      0.000038    0.000023
 247         6           4      0.000034    0.000021
 248         6           4      0.000028    0.000017
 249         6           4      0.000027    0.000016
 250         6           4      0.000024    0.000013
 251         6           4      0.000022    0.000012
 252         6           4      0.000021    0.000010
 253         6           4      0.000018    0.000008
 254         6           4      0.000018    0.000007
 255         7           3      0.000016    0.000007
 256         8           2      0.000013    0.000006
 257         8           2      0.000013    0.000005
 258         8           2      0.000012    0.000005
 259         8           2      0.000011    0.000005
 260         8           2      0.000010    0.000004
 261         8           2      0.000009    0.000004
 262         8           2      0.000009    0.000003
 263         7           3      0.000123    0.000114
 264         7           3      0.000131    0.000123
 265         7           3      0.000115    0.000108
 266         7           3      0.000111    0.000104
 267         8           2      0.000107    0.000101
 268         8           2      0.000091    0.000085
 269         8           2      0.000093    0.000086
 270         8           2      0.000084    0.000078
 271         8           2      0.000072    0.000066
 272         8           2      0.000074    0.000068
 273         9           1      0.000067    0.000062
 274         9           1      0.000065    0.000060
 275         9           1      0.000064    0.000058
 276         9           1      0.000055    0.000050
 277         9           1      0.000060    0.000054
 278         9           1      0.000056    0.000051
 279         9           1      0.000049    0.000044
 280         9           1      0.000051    0.000046
 281         9           1      0.000045    0.000040
 282         9           1      0.000042    0.000037
 283         9           1      0.000041    0.000036
 284         9           1      0.000037    0.000032
 285         9           1      0.000035    0.000029
 286         9           1      0.000033    0.000028
 287         9           1      0.000029    0.000024
 288         9           1      0.000026    0.000021
 289         9           1      0.000026    0.000021
 290         9           1      0.000023    0.000018
 291         9           1      0.000021    0.000016
 292         9           1      0.000020    0.000015
 293         9           1      0.000019    0.000014
 294         9           1      0.000017    0.000012
 295         9           1      0.000017    0.000012
 296         9           1      0.000015    0.000010
 297         9           1      0.000014    0.000009
 298         9           1      0.000014    0.000009
 299         9           1      0.000012    0.000007
 300         9           1      0.000012    0.000007
 301         9           1      0.000011    0.000006
 302         9           1      0.000010    0.000005
 303         9           1      0.000010    0.000005
 304         9           1      0.000010    0.000005
 305         9           1      0.000009    0.000004
 306         9           1      0.000009    0.000004
 307         9           1      0.000009    0.000004
 308         9           1      0.000008    0.000003
 309         9           1      0.000008    0.000004
 310         9           1      0.000008    0.000003
 311         9           1      0.000008    0.000003
 312         9           1      0.000008    0.000003
 313         9           1      0.000007    0.000002
 314         9           1      0.000007    0.000002
 315         9           1      0.000007    0.000002
 316         9           1      0.000007    0.000002
 317         9           1      0.000007    0.000002
 318         9           1      0.000007    0.000002
 319         9           1      0.000006    0.000001
 320         9           1      0.000006    0.000001
 321         9           1      0.000006    0.000001
 322        10           0      0.000006    0.000001    Roots Converged
 ---------------------------------------------------
WARNING: wavefunction analysis only for HOMO-Fragments
  
Fragment index for active (RAS2) orbitals
 | ALPHA  | BETA   |
--------------------------------------------------
 | 111133 | 111133 | 
   
**************************************************
 RAS-CI total energy for state   1:  -4295.228709269719
  Excitation energy (eV) =    0.0000
  Multiplicity: Singlet 
  Dipole Moment:  0.0115 X   0.7358 Y   0.2803 Z
  Amplitudes : 
  
 | HOLE  | ALPHA  | BETA   | PART  |    AMPLITUDE 
--------------------------------------------------
 |       | 110010 | 110001 |       |     0.1525468
 |       | 110010 | 101010 |       |     0.1277512
 |       | 110010 | 101001 |       |     0.2298422
 |       | 110010 | 001101 |       |    -0.1335155
 |       | 110001 | 110010 |       |     0.1525443
 |       | 110001 | 101010 |       |     0.2298399
 |       | 110001 | 101001 |       |     0.1185236
 |       | 110001 | 001110 |       |    -0.1335129
 |       | 101010 | 110010 |       |     0.1277411
 |       | 101010 | 110001 |       |     0.2298312
 |       | 101010 | 101001 |       |     0.1359707
 |       | 101010 | 010101 |       |    -0.1777487
 |       | 101010 | 001101 |       |    -0.1242801
 |       | 101001 | 110010 |       |     0.2298369
 |       | 101001 | 110001 |       |     0.1185268
 |       | 101001 | 101010 |       |     0.1359618
 |       | 101001 | 010110 |       |    -0.1777506
 |       | 101001 | 001110 |       |    -0.1242751
 |       | 010110 | 101001 |       |    -0.1777408
 |       | 010101 | 101010 |       |    -0.1777469
 |       | 001110 | 110001 |       |    -0.1335097
 |       | 001110 | 101001 |       |    -0.1242778
 |       | 001101 | 110010 |       |    -0.1335152
 |       | 001101 | 101010 |       |    -0.1242726
--------------------------------------------------
*** Contributions RASCI wfn    Active:  90.89
                                 Hole:   4.35
                                 Part:   4.77
*** Unpaired Electrons
 Yamaguchi:      1.61
  
*** Fragment decomposition for state:   1
--------------------------------------------------
*** Fragment weights
   GS     LE     ME     CR    Total
0.0000 0.0000 0.0000 1.0000  1.0000
  
Local Excitons (LE)
 Fragment   Weight
     1      0.0000
     2      0.0000
     3      0.0000
 Total      0.0000
  
Multiple Excitons (ME)
  Dimer     Weight  DE(TT)  DE(SS)
  1, 2      0.0000  0.0000  0.0000
  1, 3      0.0000  0.0000  0.0000
  2, 3      0.0000  0.0000  0.0000
 ------------------
Dimers      0.0000
+2-mer      0.0000
 Total      0.0000
  
Charge Resonances (CR)
Pair CR 
  A --> B              B --> A               Total
  1 --> 2    0.0000    2 --> 1    0.9997     0.9997
  1 --> 3    0.0000    3 --> 1    0.0000     0.0000
  2 --> 3    0.0000    3 --> 2    0.0000     0.0000
 ------------------
  Pair CR   0.9997
+2-mer CR   0.0003
 Total CR   1.0000
  
 Fragment  # electrons
    1      174.0000
    2      170.0000
    3      172.0000
  
 Fragment Cumulant Charge Matrix
  
   Fragm  |      1         2         3
       1  | -173.9998   -0.0002   -0.0000
       2  |   -0.0002 -169.9996   -0.0003
       3  |   -0.0000   -0.0003 -171.9997
  
 Fragment Cumulant Spin Matrix
  
   Fragm  |      1         2         3
       1  |    0.0000   -0.0000   -0.0000
       2  |   -0.0000    0.0001   -0.0001
       3  |   -0.0000   -0.0001    0.0001
  
 Doubly Excited Fragment Cumulant Spin Matrix
  
   Fragm  |      1         2         3
       1  |    0.0000    0.0000    0.0000
       2  |    0.0000    0.0000    0.0000
       3  |    0.0000    0.0000    0.0000
  
 Triply Excited Fragment Cumulant Spin Matrix
  
   Fragm  |      1         2         3
       1  |    0.0000    0.0000    0.0000
       2  |    0.0000    0.0000    0.0000
       3  |    0.0000    0.0000    0.0000
  
**************************************************
 RAS-CI total energy for state   2:  -4295.188868736514
  Excitation energy (eV) =    1.0841
  Multiplicity: Triplet 
  Dipole Moment:  0.0191 X   0.7244 Y   0.2851 Z
  Trans. Moment:  0.0003 X  -0.0001 Y   0.0000 Z
  Strength   :  0.000000
  Amplitudes : 
  
 | HOLE  | ALPHA  | BETA   | PART  |    AMPLITUDE 
--------------------------------------------------
 |       | 110010 | 110001 |       |     0.1750041
 |       | 110010 | 101001 |       |     0.2630859
 |       | 110010 | 001101 |       |    -0.1528028
 |       | 110001 | 110010 |       |    -0.1750042
 |       | 110001 | 101010 |       |    -0.2631034
 |       | 110001 | 001110 |       |     0.1528395
 |       | 101010 | 110001 |       |     0.2631073
 |       | 101010 | 101001 |       |     0.1561643
 |       | 101010 | 010101 |       |    -0.2030593
 |       | 101010 | 001101 |       |    -0.1424551
 |       | 101001 | 110010 |       |    -0.2630905
 |       | 101001 | 101010 |       |    -0.1561639
 |       | 101001 | 010110 |       |     0.2030746
 |       | 101001 | 001110 |       |     0.1424805
 |       | 010110 | 101001 |       |    -0.2030789
 |       | 010101 | 101010 |       |     0.2030642
 |       | 001110 | 110001 |       |    -0.1528339
 |       | 001110 | 101001 |       |    -0.1424717
 |       | 001101 | 110010 |       |     0.1527993
 |       | 001101 | 101010 |       |     0.1424475
--------------------------------------------------
*** Contributions RASCI wfn    Active:  92.46
                                 Hole:   3.48
                                 Part:   4.07
*** Unpaired Electrons
 Yamaguchi:      2.94
  
*** Fragment decomposition for state:   2
--------------------------------------------------
*** Fragment weights
   GS     LE     ME     CR    Total
0.0000 0.0000 0.0000 1.0000  1.0000
  
Local Excitons (LE)
 Fragment   Weight
     1      0.0000
     2      0.0000
     3      0.0000
 Total      0.0000
  
Multiple Excitons (ME)
  Dimer     Weight  DE(TT)  DE(SS)
  1, 2      0.0000  0.0000  0.0000
  1, 3      0.0000  0.0000  0.0000
  2, 3      0.0000  0.0000  0.0000
 ------------------
Dimers      0.0000
+2-mer      0.0000
 Total      0.0000
  
Charge Resonances (CR)
Pair CR 
  A --> B              B --> A               Total
  1 --> 2    0.0000    2 --> 1    1.0000     1.0000
  1 --> 3    0.0000    3 --> 1    0.0000     0.0000
  2 --> 3    0.0000    3 --> 2    0.0000     0.0000
 ------------------
  Pair CR   1.0000
+2-mer CR   0.0000
 Total CR   1.0000

Speeding up ADC(2) calculations

@fplasser Felix Plasser — Tue, 17 Mar 2026 11:13:06 +0000

Hi,

Yes, for a large basis set, it is probably a good idea to use RI.

Also, the memory is extremely important for ADC. If you don’t have enough memory, then the job will still run but it will spend most of its time in disk I/O. So, I would check with top whether the job actually runs on the appropriate number of cores.

Speeding up ADC(2) calculations

@jherbert John Herbert — Mon, 16 Mar 2026 11:41:45 +0000

You can try RI with ADC,
https://manual.q-chem.com/latest/sec_ADC_RI.html

In addition, for your SCF linear dependency problem a better solution (as compared to BASIS_LIN_DEP_THRESH) is to increase THRESH, e.g., to 14. That is what is recommended for diffuse basis functions, here:
https://doi.org/10.1021/acs.jpca.4c00283

Speeding up ADC(2) calculations

@derik_rochlitzer — Mon, 16 Mar 2026 11:19:34 +0000

Hello,

I need to perform scans of excited states along some normal modes using ADC(2). Due to the volume of jobs I must process, I was wondering if there are any key points that I am missing to speed up the calculations, beyond assigning threads and memory. My current $rem section is:

METHOD ADC(2)
BASIS aug-cc-pVTZ
EE_SINGLETS 26
CC_SYMMETRY FALSE
ADC_DAVIDSON_MAXITER 500
BASIS_LIN_DEP_THRESH 4

MEM_TOTAL 64000
MEM_STATIC 2000

I could reduce the number of states to 20, but I would prefer to keep as many as possible. Additionally, I needed to set BASIS_LIN_DEP_THRESH because certain geometries cause the SCF to misbehave, ADC_DAVIDSON_MAXITER to ensure that my excited states are converged, and CC_SYMMETRY FALSE since scanning breaks the symmetry of the molecule.

Thank you in advance for any advice!

Is it possible to print gradients of several excited states?

@jherbert John Herbert — Sat, 14 Mar 2026 13:36:54 +0000

In that special case, a semi-hack that you could do would be to run one step of a MECP optimization, because that job prints the gradient for both states to be optimized.
https://manual.q-chem.com/latest/sect_MECP.html

Is it possible to print gradients of several excited states?

@pavel — Fri, 13 Mar 2026 04:51:09 +0000

Thank you! This idea will work if the electronic states are not degenerate. However, for the degenerate electronic states this may not work because the subsequent diagonalizations may deliver different eigenvectors spanning the same degenerate subspace.

Is it possible to print gradients of several excited states?

@jherbert John Herbert — Fri, 13 Mar 2026 00:08:53 +0000

Not that I’m aware of but you can always set it up as multiple jobs in the same input file, use SCF_GUESS = READ in the subsequent jobs. Shouldn’t be much extra effort since the CPSCF equations would need to be solved for each excited state anyway.

Is it possible to print gradients of several excited states?

@pavel — Thu, 12 Mar 2026 21:05:28 +0000

I am wondering whether it is possible to run only one Q-Chem calculation that would produce gradients of several TDDFT states. It looks like a TDDFT calculation with

JOBTYPE = FORCE

requests CIS_STATE_DERIV, which can be specified only to a specific state.

I can see a selector of several states only for $derivative_coupling section, but not for gradients.

ORCA, for example, has such gradient selectors (SGRADLIST and TGRADLIST).

Thanks!

Memory and RICIS(D) calculations

@juanes Juan Esteban Arias-Martinez — Wed, 11 Mar 2026 16:19:28 +0000

Got it, thank you for your input regardless. Update: the non-RI CIS(D) ran to completion.

Memory and RICIS(D) calculations

@jherbert John Herbert — Wed, 11 Mar 2026 10:08:05 +0000

Sorry, I also meant to say: It’s possible that RI-CIS(D) is still using MEM_STATIC rather than MEM_TOTAL. A lot of that code, which was written in the mid-2000s, is based on the old version of the MP2 (before the mid-2010s rewrite), and the old MP2 code used MEM_STATIC and AO2MO_DISK. I’m not sure about any of this without looking inside but based on the history, these are my guesses.

Memory and RICIS(D) calculations

@juanes Juan Esteban Arias-Martinez — Wed, 11 Mar 2026 00:01:34 +0000

According to the nodes available to me,

~$ free -m
              total        used        free      shared  buff/cache   available
Mem:         192070        1520      189428           0        1121      189221
Swap:         31249          45       31204

I tried giving

$rem
  METHOD          RICIS(D)
  BASIS           cc-pVDZ
  AUX_BASIS       RIMP2-cc-pVDZ
  MEM_TOTAL       192000
  AO2MO_DISK      192000
  MEM_STATIC      2000
  CIS_N_ROOTS     3
  CIS_TRIPLETS    FALSE
  SCF_CONVERGENCE 8
  THRESH          14
$end

and still got

 RI-CIS(D) job begins now...

Calculating maximum allowed batch size for RI-CIS(D)
 Memory available: 191999 MB
 Disk   available: 192000 MB
 Maximum batch size: 116 (Allowed from memory: 313/ disk: 436)
 Memory required:  -3666 MB
 Disk   required:  56005 MB

Form (P|Q)**(-1/2)...
Forming (pq|P)...
 

 Q-Chem warning in module libmdc/NewQAlloc.C, line 469:

 QAllocGeneral() returns a null pointer when allocating 18446744069769369280 Bytes memory


 Q-Chem fatal error occurred in module libmdc/newfileman.C, line 348:

 FileMan error: End of file reached prematurely reading (5004544) bytes in file FILE_VIAQ_INTS
 Path: /scratch/jearias/AO2MO.20260310170116/617.0


 Please submit a crash report at q-chem.com/reporter

Interestingly, the non-RI version

$rem
  METHOD          CIS(D)  
  BASIS           cc-pVDZ
  MEM_TOTAL       120000
  MEM_STATIC      2000
  AO2MO_DISK      32000
  CIS_N_ROOTS     3
  CIS_TRIPLETS    FALSE
  SCF_CONVERGENCE 8
  THRESH          14
$end

seems to at the very least be running.

Memory and RICIS(D) calculations

@jherbert John Herbert — Tue, 10 Mar 2026 23:39:17 +0000

Try setting AO2MO_DISK to the max size of your disk. This looks like the old semi-direct MP2 code (now seemily deprecated for MP2, sadly) where you could always compromise between memory and disk. AO2MO_DISK is the disk space allowed for the 4-index integral transformation.

Memory and RICIS(D) calculations

@juanes Juan Esteban Arias-Martinez — Tue, 10 Mar 2026 22:59:09 +0000

I am trying to test a RICIS(D) calculation on a 38-atom molecule and am having issues understanding whether it is possible or not.

$molecule
  0   1
  S  -1.629783     1.486780     1.602787
  C  -3.172502     0.660737     1.707813
  C  -3.171184    -0.671275     1.715410
  S  -1.626373    -1.494026     1.616410
  C  -0.672927    -0.002912     1.566063
  C   0.668335    -0.002912     1.561352
  S   1.628459     1.484068     1.572165
  C   3.166985     0.659479     1.699600
  C   3.186469    -0.674950     1.725186
  S   1.624518    -1.488871     1.603089
  H  -4.067465     1.275986     1.756352
  H  -4.064939    -1.287750     1.770649
  H   4.056837     1.280344     1.774784
  C   4.396566    -1.534518     1.921570
  C  -0.674382     1.248928    -1.603512
  C   0.667355     1.254227    -1.601682
  C   1.423987     0.008538    -1.556222
  C   0.676999    -1.243114    -1.602489
  C  -0.664712    -1.248318    -1.602697
  C  -1.421474    -0.002388    -1.555263
  C  -2.783555    -0.008233    -1.471895
  C  -3.542008     1.209629    -1.409803
  C  -3.532327    -1.232067    -1.410597
  C   2.785871     0.014766    -1.472754
  C   3.537145     1.236832    -1.413692
  C   3.542932    -1.203270    -1.414911
  N  -4.141245     2.196106    -1.343501
  N  -4.124340    -2.222918    -1.344413
  N   4.135288     2.224096    -1.349107
  N   4.139045    -2.192161    -1.355305
  H  -1.227484     2.184990    -1.626392
  H  -1.210300    -2.188862    -1.625422
  H   1.213657     2.194190    -1.623971
  H   1.229804    -2.179290    -1.626254
  H   4.394358    -2.385786     1.233493
  H   5.295973    -0.949244     1.703792
  S   4.598251    -2.114493     3.642597
  H   3.499525    -2.895097     3.677215
$end

$rem
  METHOD          RICIS(D)
  BASIS           cc-pVDZ
  AUX_BASIS       RIMP2-cc-pVDZ
  MEM_TOTAL       120000
  AO2MO_DISK      50000
  MEM_STATIC      2000
  CIS_N_ROOTS     3
  CIS_TRIPLETS    FALSE
  SCF_CONVERGENCE 8
  THRESH          14
$end

First, the $rem variable

AO2MO_DISK

seems to be used throughout different examples in the manual but never really explained. Second, I am confused in regards to what MEM_STATIC and MEM_TOTAL should be set to. Section 7.9.7 RI-CIS(D), SOS-CIS(D), and SOS-CIS(D0 ): Job Control in the manual says:

At least 150(N^2+N)D of MEM_STATIC is required (N: number of basis functions, D: size of a double precision storage, usually 8). Because a number of matrices with N^2 size also need to be stored, 32–160 MB of additional MEM_STATIC is needed.

In the example above,

 Molecular Point Group                 C1    NOp =  1
 Largest Abelian Subgroup              C1    NOp =  1
 Nuclear Repulsion Energy =        3450.86728495 hartrees
 There are      116 alpha and      116 beta electrons
 Requested basis set is cc-pVDZ
 There are 208 shells and 462 basis functions

 Total QAlloc Memory Limit 120000 MB
 Mega-Array Size      1956 MB
 MEM_STATIC part      2000 MB

so N = 462, and according to the formula in the manual, MEM_STATIC should be set to 256687200 which seems very high to me. Example 7.64 in the manual

$molecule
   0 1
   C     0.667472     0.000000     0.000000
   C    -0.667472     0.000000     0.000000
   H     1.237553     0.922911     0.000000
   H     1.237553    -0.922911     0.000000
   H    -1.237553     0.922911     0.000000
   H    -1.237553    -0.922911     0.000000
$end

$rem
   METHOD          ricis(d)
   BASIS           aug-cc-pVDZ
   MEM_TOTAL       1000
   MEM_STATIC      100
   AO2MO_DISK      1000
   AUX_BASIS       rimp2-aug-cc-pVDZ
   PURECART        1111
   CIS_N_ROOTS     10
   CIS_SINGLETS    true
   CIS_TRIPLETS    false
$end

has 82 basis functions which, per that formula, requires 8167200 of MEM_STATIC when, clearly, 100 is enough. Is the formula given in the manual wrong or am I misunderstanding it? When I try to run my calculation, I get

 RI-CIS(D) job begins now...

Calculating maximum allowed batch size for RI-CIS(D)
 Memory available: 119999 MB
 Disk   available: 50000 MB
 Maximum batch size: 101 (Allowed from memory: 245/ disk: 101)
 Memory required:  -10185 MB
 Disk   required:  49648 MB

Form (P|Q)**(-1/2)...
Forming (pq|P)...


 Q-Chem warning in module libmdc/NewQAlloc.C, line 469:

 QAllocGeneral() returns a null pointer when allocating 18446744062933890160 Bytes memory


 Q-Chem fatal error occurred in module libmdc/newfileman.C, line 348:

 FileMan error: End of file reached prematurely reading (5004544) bytes in file FILE_VIAQ_INTS
 Path: /scratch/jearias/AO2MO.20260310152610/617.0


 Please submit a crash report at q-chem.com/reporter

18446744062933890160 bytes of memory is obviously outside of my limits but the line Memory required: -10185 MB makes me believe I am missing some memory-related keyword or not properly adjusting the values and perhaps the calculation is indeed possible.

Any help would be appreciated.

MRSF: differences between Q-Chem and OpenQP

@AnnaKrylov Anna Krylov — Sun, 08 Mar 2026 15:02:55 +0000

It was brought to our attention that our implementation of MRSF-TDDFT and regular SF-TDDFT yield results that differ from those of OpenQP for H2. We traced the difference to how the beta Fock matrix is computed for the case when there are no beta electrons. In Q-Chem we treat the derivative of the exchange-correlation functional for zero density as zero. Following a different line of reasoning, the OpenQP team arrived at the nonzero contributions to the Fock matrix from zero density. We believe our approach is more rigorous, however, we acknowledge that the alternative reasoning also has logic. Hence, the disagreement for this particular case between the two packages should be treated as a legitimate difference in formalisms. We emphasize that for all other cases the agreement is very good (differences are less than 0.001 eV).

SOC for unrestricted TDDFT

@pavel — Fri, 06 Mar 2026 12:14:02 +0000

Building SOMF, unfortunately, takes time. There may be computational improvements in the future. Currently, I would recommend using more OpenMP threads to speed it up.

Gradient and Hessian using CCSD and EOM-CCSD

@AnnaKrylov Anna Krylov — Thu, 05 Mar 2026 19:56:16 +0000

It depends on what you want. If you just need gradient or Hessian at the particular structure, you can do it the way I described. If you want to have optimized structure and then frequencies, you first do JOBTYPE=OPT, read geometry, and do JOBTYPE=FREQ.

Gradient and Hessian using CCSD and EOM-CCSD

@Ayan_Bhowmick Ayan Bhowmick — Thu, 05 Mar 2026 19:34:10 +0000

Dear Ma’am,

So I need to do a OPT followed by a FORCE and FREQ calculation. Am I correct?

Gradient and Hessian using CCSD and EOM-CCSD

@AnnaKrylov Anna Krylov — Thu, 05 Mar 2026 17:59:26 +0000

JOBTYPE = FORCE will give you the gradient. If you do EOM-CCSD, you will need to add cc_state_to_opt to specify for which EOM state you need the gradient. For oxygen, you may want to use EOM-SF-CCSD.

Analytic second derivatives are not yet implemented, so when you specify JOBTYPE = FREQ, the code will compute numeric Hessian by finite differences of first derivatives. In this calculation, you will need to turn off the symmetry.

There are examples of these calculations in the manual and in $QC/samples.

Gradient and Hessian using CCSD and EOM-CCSD

@Ayan_Bhowmick Ayan Bhowmick — Thu, 05 Mar 2026 13:19:31 +0000

How to get gradient and hessian for Ground state and Exited state [0,0,0,0,0,1,0,0] of O2 using CCSD and EOM-CCSD?

Resolution of identity for CDFT?

@jherbert John Herbert — Tue, 03 Mar 2026 03:16:02 +0000

Use SOLVENT_METHOD = PCM with RI-SCF keywords, gives message. (I think I put the message there some time ago.)

Resolution of identity for CDFT?

@crinperizer — Mon, 02 Mar 2026 21:44:20 +0000

Got it, thanks for reporting that. I was able to get RI-J + occ-RI-K + SMD to run normally with USE_LIBQINTS = TRUE and CDFT off. It converged to something resembling the desired CDFT state, so this may be usable, but I don’t know what downstream implications the use of LIBQINTS would have (just because it ran without crashing doesn’t mean what I did is legal).

With USE_LIBQINTS = TRUE and CDFT on again, it crashes with:

free(): invalid size
/global/homes/s/foo/qchem: line 122: 638175 Aborted                 ${QCPROG_S} ${inp} ${scr}
Error in Q-Chem run part 1
Error in the Q-Chem run

Which settings did you see the SOLVENT_METHOD = PCM warning for?

Resolution of identity for CDFT?

@jherbert John Herbert — Sun, 01 Mar 2026 15:08:36 +0000

Based on some experimentation, this appears to be an incompatibility between RI and the solvation model. For SOLVENT_METHOD = PCM you get a message to that effect, but that doesn’t get triggered here (although it should). I will submit a ticket.

Resolution of identity for CDFT?

@crinperizer — Sun, 01 Mar 2026 01:28:29 +0000

Oddly enough, with CDFT removed there is still a crash.

$molecule
1 2
C      6.30855022     -4.93788338      3.88865279
H      6.46844030     -5.83477413      3.28091071
C      5.01765030     -4.35035744      4.19205135
H      4.04802354     -4.72207231      3.84570655
C      5.23841495     -3.22386205      5.02651884
H      4.47447698     -2.55909283      5.44169462
C      6.66721159     -3.10150946      5.22621529
H      7.15976745     -2.33556271      5.83473897
C      7.31655349     -4.20719489      4.58681439
H      8.38968765     -4.41966656      4.59195632
C      6.21501810     -1.01803699      2.56079378
H      6.09904537     -0.12748159      3.18572776
C      7.47643922     -1.62182529      2.21664122
H      8.46168129     -1.27259229      2.54082808
C      7.20721274     -2.73851668      1.37478405
H      7.94488276     -3.41511989      0.93265470
C      5.78075005     -2.82732645      1.20681162
H      5.27058208     -3.57749332      0.59529050
C      5.15516226     -1.69391917      1.85096660
C      3.74477713     -1.34129407      1.83063937
C      2.79744585     -2.10924529      1.10156345
H      3.10807348     -3.02219605      0.58703002
C      1.47285868     -1.69375406      0.97701026
H      0.77759409     -2.27246231      0.35960808
C      1.05307597     -0.50071272      1.58786675
C      1.94333084      0.24494950      2.36842866
H      1.63232837      1.17047784      2.85630207
C      3.26858932     -0.17875360      2.48969492
H      3.95611436      0.43480123      3.07808950
Co      6.25310142     -2.97668890      3.20704943
N     -0.32023883     -0.01937991      1.29546237
C     -0.56952759      1.42091634      1.63016136
H      0.20840818      2.02914160      1.15160308
H     -1.55666329      1.68346606      1.22473574
H     -0.56324389      1.55048325      2.72087926
C     -1.37583337     -0.89912011      1.91359579
H     -1.21877777     -1.93280239      1.57691648
H     -1.28362197     -0.83601280      3.00726190
H     -2.36068006     -0.53706103      1.58448065
H     -0.41746428     -0.06422855      0.25424860
C      2.74081181      0.23358296     -1.33464848
C      3.07781445      1.33939183     -0.52471591
C      3.77785252     -0.57596110     -1.85603517
H      2.27171878      1.96727642     -0.13667488
H      3.54385475     -1.43198863     -2.49568935
C      4.41385497      1.62501708     -0.23428591
C      5.11313185     -0.29445065     -1.55455647
H      4.66306364      2.49129425      0.38751464
H      5.90839827     -0.93004235     -1.95696942
C      5.43472279      0.80285844     -0.73853255
H      6.48090493      1.02669988     -0.50553360
C      1.31075073     -0.06995661     -1.57864311
O      0.41861174      0.57454350     -0.99120839
C      0.93672357     -1.17041692     -2.54385239
H      1.37713004     -2.13610755     -2.23949946
H     -0.15882613     -1.26433396     -2.58213330
H      1.32148929     -0.94112848     -3.55429865
$end

$rem
METHOD       TPSSh
MEM_TOTAL    400000
JOBTYPE      opt
BASIS        def2-tzvpp
AUX_BASIS	RIJK-def2-tzvpp
SCF_CONVERGENCE 8
XC_GRID      2	SG-2
RI_J 	TRUE
OCC_RI_K 	TRUE
RI_K_GRAD 	TRUE
MAX_SCF_CYCLES 200
GEOM_OPT_MAX_CYCLES 100
SOLVENT_METHOD   smd
DFT_D        D4
NO_REORIENT  true
POINT_GROUP_SYMMETRY false
INTEGRAL_SYMMETRY    false
MOLDEN_FORMAT   TRUE
$end

$smx
solvent THF
$end

$opt
CONSTRAINT
stre  31  53  2.47538
ENDCONSTRAINT
$end

 -----------------------------------------------------------------------
  General SCF calculation program by
  Eric Jon Sundstrom, Paul Horn, Yuezhi Mao, Dmitri Zuev, Alec White,
  David Stuck, Shaama M.S., Shane Yost, Joonho Lee, David Small,
  Daniel Levine, Susi Lehtola, Hugh Burton, Evgeny Epifanovsky,
  Bang C. Huynh
 -----------------------------------------------------------------------
 Exchange:     0.1000 Hartree-Fock + 0.9000 TPSS
 Correlation:  1.0000 TPSS
 Using SG-2 standard quadrature grid
 Dispersion:   Grimme D4
 The following algorithms are not available for rij_occrik, because: 
  Algorithm libdf::reuse2e3c@0x361f8f28 for rij_occrik is not capable because of input use_libqints = false

  Algorithm libdf::recompute2e3c@0x361f8fa0 for rij_occrik is not capable because of input use_libqints = false

gen_scfman_exception: hamiltonian: algorithm selector failure

 Q-Chem fatal error occurred in module libgscf/gen_scfman/gen_scfman_main.C, line 244:

 Error in gen_scfman


 Please submit a crash report at q-chem.com/reporter

In this case, USE_LIBQINTS = TRUE had to be set to get it to run, which I wasn’t able to find documentation for.

Resolution of identity for CDFT?

@crinperizer — Sat, 28 Feb 2026 20:18:05 +0000

for sure - if that’s the case, so be it…

Resolution of identity for CDFT?

@jherbert John Herbert — Sat, 28 Feb 2026 19:52:07 +0000

Note that CDFT is implemented only in Q-Chem’s old SCF code so some of the modern accoutrements may not be available. You can tell because the title block

 -----------------------------------------------------------------------
  General SCF calculation program by
  Eric Jon Sundstrom, Paul Horn, Yuezhi Mao, Dmitri Zuev, Alec White,
  David Stuck, Shaama M.S., Shane Yost, Joonho Lee, David Small,
  Daniel Levine, Susi Lehtola, Hugh Burton, Evgeny Epifanovsky,
  Bang C. Huynh
 -----------------------------------------------------------------------

for the new SCF code is not printed in CDFT jobs.

Resolution of identity for CDFT?

@crinperizer — Sat, 28 Feb 2026 19:33:09 +0000

cloning this to a separate thread so as not to clutter previous discussion.

Having to run larger, more expensive constrained DFT jobs with hybrid functionals so I started to explore the resolution of identity-based approximations. However, I find with the following input (RI_J and occ-RI-K) that it segfaults immediately before the first SCF cycle. Using Qchem 6.3.

$molecule
   1 2
  C      6.30855022     -4.93788338      3.88865279
  H      6.46844030     -5.83477413      3.28091071
  C      5.01765030     -4.35035744      4.19205135
  H      4.04802354     -4.72207231      3.84570655
  C      5.23841495     -3.22386205      5.02651884
  H      4.47447698     -2.55909283      5.44169462
  C      6.66721159     -3.10150946      5.22621529
  H      7.15976745     -2.33556271      5.83473897
  C      7.31655349     -4.20719489      4.58681439
  H      8.38968765     -4.41966656      4.59195632
  C      6.21501810     -1.01803699      2.56079378
  H      6.09904537     -0.12748159      3.18572776
  C      7.47643922     -1.62182529      2.21664122
  H      8.46168129     -1.27259229      2.54082808
  C      7.20721274     -2.73851668      1.37478405
  H      7.94488276     -3.41511989      0.93265470
  C      5.78075005     -2.82732645      1.20681162
  H      5.27058208     -3.57749332      0.59529050
  C      5.15516226     -1.69391917      1.85096660
  C      3.74477713     -1.34129407      1.83063937
  C      2.79744585     -2.10924529      1.10156345
  H      3.10807348     -3.02219605      0.58703002
  C      1.47285868     -1.69375406      0.97701026
  H      0.77759409     -2.27246231      0.35960808
  C      1.05307597     -0.50071272      1.58786675
  C      1.94333084      0.24494950      2.36842866
  H      1.63232837      1.17047784      2.85630207
  C      3.26858932     -0.17875360      2.48969492
  H      3.95611436      0.43480123      3.07808950
 Co      6.25310142     -2.97668890      3.20704943
  N     -0.32023883     -0.01937991      1.29546237
  C     -0.56952759      1.42091634      1.63016136
  H      0.20840818      2.02914160      1.15160308
  H     -1.55666329      1.68346606      1.22473574
  H     -0.56324389      1.55048325      2.72087926
  C     -1.37583337     -0.89912011      1.91359579
  H     -1.21877777     -1.93280239      1.57691648
  H     -1.28362197     -0.83601280      3.00726190
  H     -2.36068006     -0.53706103      1.58448065
  H     -0.41746428     -0.06422855      0.25424860
  C      2.74081181      0.23358296     -1.33464848
  C      3.07781445      1.33939183     -0.52471591
  C      3.77785252     -0.57596110     -1.85603517
  H      2.27171878      1.96727642     -0.13667488
  H      3.54385475     -1.43198863     -2.49568935
  C      4.41385497      1.62501708     -0.23428591
  C      5.11313185     -0.29445065     -1.55455647
  H      4.66306364      2.49129425      0.38751464
  H      5.90839827     -0.93004235     -1.95696942
  C      5.43472279      0.80285844     -0.73853255
  H      6.48090493      1.02669988     -0.50553360
  C      1.31075073     -0.06995661     -1.57864311
  O      0.41861174      0.57454350     -0.99120839
  C      0.93672357     -1.17041692     -2.54385239
  H      1.37713004     -2.13610755     -2.23949946
  H     -0.15882613     -1.26433396     -2.58213330
  H      1.32148929     -0.94112848     -3.55429865
$end

$rem
   METHOD       TPSSh
   MEM_TOTAL    400000
   JOBTYPE      opt
   BASIS        def2-tzvpp
   AUX_BASIS	RIJK-def2-tzvpp
   SCF_CONVERGENCE 8
   XC_GRID      2	SG-2
   RI_J 	TRUE
   OCC_RI_K 	TRUE
   RI_K_GRAD 	TRUE
   MAX_SCF_CYCLES 200
   GEOM_OPT_MAX_CYCLES 100
   SOLVENT_METHOD   smd
   DFT_D        D4
   CDFT         true
   CDFT_THRESH  8
   NO_REORIENT  true
   POINT_GROUP_SYMMETRY false
   INTEGRAL_SYMMETRY    false
   MOLDEN_FORMAT   TRUE
$end

$smx
solvent THF
$end

$opt
   CONSTRAINT
   stre  31  53  2.47538
   ENDCONSTRAINT
$end

$cdft
   -1.0
   1 1 40
   1.0
   1 1 40 s
$end

/global/homes/s/foo/qchem: line 122: 2090781 Segmentation fault      ${QCPROG_S} ${inp} ${scr}
Error in Q-Chem run part 1

When the memory is lowered to 4K (in case it’s allocated per thread), a different segfault results:

corrupted double-linked list
/global/homes/s/foo/qchem: line 122: 2357577 Aborted                 ${QCPROG_S} ${inp} ${scr}
Error in Q-Chem run part 1
Error in the Q-Chem run

Last time I tried this with def2-SVP on 6.2.1, it barely squeaks out the first SCF cycle before a similar segfault.

With RI_J set to false (so only occ-RI-K and the corresponding gradient) the job runs but very slowly, 8 hours for 2 converged SCF cycles. With def2-SVP, it’s about an hour per converged SCF cycle. The analytical gradients didn’t seem to be available in any of these cases for CDFT.

Just running the hybrid functional CDFT without the RI approximations, the opt job runs and completes normally with def2-TZVPP and takes about 20 node-hours for 25 geometry steps. I could afford to use it for a few single point calculations but not for the full dataset.

Possibly all of this is a CDFT issue so I am trying a test job without.

ROHF energy discrepancy between Q-Chem and CFOUR

@pavel — Sat, 28 Feb 2026 15:56:57 +0000

Some programs have discrepancies in evaluations of the nuclear repulsion energy:

github.com/pyscf/pyscf

difference b/t NWCHEM & pyscf TDDFT

opened 02:23PM - 16 Nov 20 UTC

closed 05:07PM - 27 Mar 23 UTC

zww-4855

bug

Hi all, I have attached nwchem and pyscf input and output files. The ground …state SCF energy is relatively close; the nuclear repulsion seems to be slightly different but I assume one of the two programs is truncating the coordinates. The are two discrepancies I have notice between pyscf and nwchem TDDFT: 1) Take the excited triplets as an example. Nwchem labels the irrep of the lowest energy roots differently than pyscf; I was hoping someone could explain why. 2) Also, nwchem shows a negative excitation energy for the 'lowest' energy triplet state that pyscf does not show. Does pyscf omit negative roots? I tried following the pyscf example to check the stability, but the software finds none. I was hoping someone could lend me some advice on how to resolve this matter. To be clear, Nwchem shows the following roots: ``` ---------------------------------------------------------------------------- Root 1 triplet b3u -0.000559002 a.u. -0.0152 eV ---------------------------------------------------------------------------- Transition Moments Spin forbidden Oscillator Strength Spin forbidden Occ. 111 b2g --- Virt. 114 b1u -0.07023 Occ. 112 au --- Virt. 113 b3g -0.99417 ---------------------------------------------------------------------------- Root 2 triplet b1g 0.027079901 a.u. 0.7369 eV ---------------------------------------------------------------------------- Transition Moments Spin forbidden Oscillator Strength Spin forbidden Occ. 111 b2g --- Virt. 113 b3g 0.78690 Occ. 112 au --- Virt. 114 b1u 0.60669 ``` whereas pyscf shows the following 2: ``` ** Triplet excitation energies and oscillator strengths ** Excited State 1: B3g 0.73674 eV 1682.87 nm f=0.0000 111 -> 113 -0.55685 112 -> 114 -0.42845 Excited State 2: B3g 0.98210 eV 1262.43 nm f=0.0000 111 -> 113 -0.43220 112 -> 114 0.55948 ``` Thanks! Zachary Windom [issue.zip](https://github.com/pyscf/pyscf/files/5546796/issue.zip)

I would recommend comparing with PySCF using mole.get_enuc() and observing what it gives in your case.

Optimal settings for large DFT calculations

@jherbert John Herbert — Sat, 28 Feb 2026 13:56:38 +0000

can you provide a small sample input?

Optimal settings for large DFT calculations

@crinperizer — Sat, 28 Feb 2026 05:34:14 +0000

The current recommendation in the manual (4.6.8) is to set “RI_J false” with occ-RI-K - are these two approximations compatible for geometry optimization at this time? I just get a segfault with 6.3 when I attempt to use RI-J and occ-RI-K at the same time.

Using FRAGMO with ptSS-PCM and CDFT for Vertical Electron Transfer Calculation

@jherbert John Herbert — Thu, 26 Feb 2026 19:47:47 +0000

I’m not sure that this is available. The file number that’s triggering the problem is designed for transferring the electrostatic potential from the first job to the second, but then the 2nd job starts with a fragment calculation that differently sized.

Using FRAGMO with ptSS-PCM and CDFT for Vertical Electron Transfer Calculation

@Hridita_Purba_Saha Hridita Purba Saha — Thu, 26 Feb 2026 19:18:49 +0000

The first job ran successfully. I got the error for the second job while it was handling the 1st fragment. The error message looks something like this:
Q-Chem fatal error occurred in module libmdc/newfileman.C, line 348:

FileMan error: End of file reached prematurely reading (16488) bytes in file UNKNOWN FILE
Path: /scratch1/hsaha/scratch/qchem/qchem577026//Frg1/8878.0

Please submit a crash report at Q-Chem Crash Reporter

Q-Chem fatal error occurred in module gesman/frgmchild.C, line 693:

Error executing Q-Chem for fragment 1

Please submit a crash report at Q-Chem Crash Reporter

Error in Q-Chem run part 2
remove work dirs /scratch1/hsaha/scratch/qchem/qchem577026.0 – /scratch1/hsaha/scratch/qchem/qchem577026.0
rm -rf /scratch1/hsaha/scratch/qchem/qchem577026.0
rm -rf /scratch1/hsaha/scratch/qchem/qchem577026
Error in the Q-Chem run

Using FRAGMO with ptSS-PCM and CDFT for Vertical Electron Transfer Calculation

@jherbert John Herbert — Thu, 26 Feb 2026 12:19:28 +0000

What is the error? And if possible, please prepare a small-molecule example that’s easier for testing (i.e., same $rem etc. but different molecule).

Using FRAGMO with ptSS-PCM and CDFT for Vertical Electron Transfer Calculation

@Hridita_Purba_Saha Hridita Purba Saha — Wed, 25 Feb 2026 20:30:14 +0000

Hi everyone,I am performing a vertical electron transfer calculation using SS-PCM (rf_ptss_save/read) in a two-step procedure:

First job: TDDFT (CAM-B3LYP) single-point calculation with CPCM, saving the non-equilibrium solvent polarization using
rf_ptss_save = true.
Second job: Product-state single-point calculation using CDFT (with charge constraints), where I read the solvent polarization using
rf_ptss_read = true and SCF_GUESS = READ.
With the current approach, I am able to obtain results. However, I would like to set up the second step using the FRAGMO method instead of CDFT, because in the CDFT calculation I observe self-interaction contributions that may be affecting the energetics. But with FRAGMO method I am getting error. Can someone help me with this? I am sharing my input file:
$molecule
0 1
H -2.3947597 -2.6409220 -0.2454001
C -3.0518069 -1.7876196 -0.1277040
C -2.5125863 -0.4667684 -0.1623793
C -3.4659280 0.5866937 -0.0228681
H -3.1378048 1.6191429 -0.0553140
C -4.8162386 0.3352052 0.1475658
H -5.4984939 1.1751432 0.2496615
C -5.3112673 -0.9697263 0.1886599
H -6.3705717 -1.1609066 0.3223051
C -4.4032394 -2.0228000 0.0428483
H -4.7605915 -3.0491406 0.0605752
C -1.1053100 -0.2148207 -0.2990558
C -0.5567698 1.1104637 -0.3888651
C 0.7860462 1.3486905 -0.4907584
C 1.7545655 0.2955413 -0.5189614
C 1.2112801 -1.0264213 -0.4933254
C -0.1296088 -1.2684151 -0.3778886
C 3.1795211 0.5520356 -0.6221959
C 3.7294912 1.8318580 -0.3632027
C 5.0893338 2.0753459 -0.4635083
C 5.9749575 1.0595061 -0.8232920
C 5.4595600 -0.2102991 -1.0825247
C 4.1004707 -0.4610785 -0.9865479
H -1.2215805 1.9668608 -0.3977569
H 1.1162003 2.3785291 -0.5786257
H 1.8812596 -1.8793355 -0.5183401
H -0.4526656 -2.3026609 -0.3423568
H 3.0794702 2.6419450 -0.0522110
H 5.4662808 3.0716106 -0.2494934
H 7.0398354 1.2526379 -0.8999823
H 6.1274663 -1.0166352 -1.3726637
H 3.7401883 -1.4559559 -1.2228686
N -0.5493130 -0.1222658 2.7468223
C 0.8886422 -0.1638791 2.7153696
C 1.5679838 0.5397708 3.8926644
C -1.2936050 -1.3517403 2.9464583
C -1.0600668 -1.9865012 4.3205058
C -1.2451067 1.1436980 2.8729565
C -1.7697236 1.4268815 4.2829139
H 1.2162543 0.3025379 1.7719636
H 1.1884373 -1.2109927 2.6697941
H 1.3265395 1.6039954 3.9253812
H 2.6490548 0.4443409 3.7727555
H 1.2827434 0.0846894 4.8435882
H -0.9864791 -2.0489919 2.1634966
H -2.3500338 -1.1294744 2.7960813
H -0.0076690 -2.2375020 4.4696957
H -1.6390550 -2.9106524 4.3777440
H -1.3806515 -1.3285182 5.1297210
H -2.0887181 1.1132129 2.1758088
H -0.5662601 1.9305654 2.5446317
H -2.5062600 0.6828014 4.5932736
H -2.2605376 2.4025735 4.2764386
H -0.9624457 1.4507261 5.0172042
$end
$rem
JOB_TYPE = SP
METHOD = CAMB3LYP
BASIS = 6-31G(d,p)
DFT_D = D3
CIS_N_ROOTS = 3
CIS_SINGLETS = TRUE
CIS_TRIPLETS = FALSE
RPA = TRUE
CIS_STATE_DERIV = 1
SOLVENT_METHOD = PCM
SCF_CONVERGENCE = 8
$end

$pcm
theory iefpcm
rf_ptss_save true
$end

$solvent
Dielectric 37.5
OpticalDielectric 1.8068
$end

@@@

$molecule
0 1
– OPP
-1 2
H -2.3947597 -2.6409220 -0.2454001
C -3.0518069 -1.7876196 -0.1277040
C -2.5125863 -0.4667684 -0.1623793
C -3.4659280 0.5866937 -0.0228681
H -3.1378048 1.6191429 -0.0553140
C -4.8162386 0.3352052 0.1475658
H -5.4984939 1.1751432 0.2496615
C -5.3112673 -0.9697263 0.1886599
H -6.3705717 -1.1609066 0.3223051
C -4.4032394 -2.0228000 0.0428483
H -4.7605915 -3.0491406 0.0605752
C -1.1053100 -0.2148207 -0.2990558
C -0.5567698 1.1104637 -0.3888651
C 0.7860462 1.3486905 -0.4907584
C 1.7545655 0.2955413 -0.5189614
C 1.2112801 -1.0264213 -0.4933254
C -0.1296088 -1.2684151 -0.3778886
C 3.1795211 0.5520356 -0.6221959
C 3.7294912 1.8318580 -0.3632027
C 5.0893338 2.0753459 -0.4635083
C 5.9749575 1.0595061 -0.8232920
C 5.4595600 -0.2102991 -1.0825247
C 4.1004707 -0.4610785 -0.9865479
H -1.2215805 1.9668608 -0.3977569
H 1.1162003 2.3785291 -0.5786257
H 1.8812596 -1.8793355 -0.5183401
H -0.4526656 -2.3026609 -0.3423568
H 3.0794702 2.6419450 -0.0522110
H 5.4662808 3.0716106 -0.2494934
H 7.0398354 1.2526379 -0.8999823
H 6.1274663 -1.0166352 -1.3726637
H 3.7401883 -1.4559559 -1.2228686
– TEA
1 2
N -0.5493130 -0.1222658 2.7468223
C 0.8886422 -0.1638791 2.7153696
C 1.5679838 0.5397708 3.8926644
C -1.2936050 -1.3517403 2.9464583
C -1.0600668 -1.9865012 4.3205058
C -1.2451067 1.1436980 2.8729565
C -1.7697236 1.4268815 4.2829139
H 1.2162543 0.3025379 1.7719636
H 1.1884373 -1.2109927 2.6697941
H 1.3265395 1.6039954 3.9253812
H 2.6490548 0.4443409 3.7727555
H 1.2827434 0.0846894 4.8435882
H -0.9864791 -2.0489919 2.1634966
H -2.3500338 -1.1294744 2.7960813
H -0.0076690 -2.2375020 4.4696957
H -1.6390550 -2.9106524 4.3777440
H -1.3806515 -1.3285182 5.1297210
H -2.0887181 1.1132129 2.1758088
H -0.5662601 1.9305654 2.5446317
H -2.5062600 0.6828014 4.5932736
H -2.2605376 2.4025735 4.2764386
H -0.9624457 1.4507261 5.0172042
$end

$rem
BASIS = 6-31G(d,p)
GUI = 2
JOB_TYPE = SP
METHOD = CAMB3LYP
SCF_CONVERGENCE = 8
SOLVENT_METHOD = PCM
SCF_GUESS = FRAGMO
SCF_PRINT_FRGM = TRUE
DFT_D = D3
MEM_TOTAL = 248000
MEM_STATIC = 4000
$end

$pcm
theory iefpcm
rf_ptss_read true
$end

$solvent
Dielectric 37.5
OpticalDielectric 1.8068
$end

Geometry Optimization with SS_PCM

@jherbert John Herbert — Wed, 25 Feb 2026 11:21:49 +0000

Sometimes one hits instabilities upon moving away from the ground-state geometry on an excited-state potential surface, as discussed here:
https://doi.org/10.1016/B978-0-323-91738-4.00005-1
Often there’s nothing to be done, it’s inherent, and can be more of a problem for functionals with a large fraction of exact exchange, including RSH functionals like CAM-B3LYP. I suggest making the Tamm-Dancoff approximation (RPA=FALSE) to avoid this. There’s not much to be gained by using RPA=TRUE.

Geometry Optimization with SS_PCM

@Hridita_Purba_Saha Hridita Purba Saha — Wed, 25 Feb 2026 04:09:04 +0000

Hi, I am encountering failures during excited-state geometry optimization using SS-PCM in Q-Chem. With internally iterative SS-PCM (IISS-PCM), the job stops with an “Imaginary RPA root detected (ω² < 0)” error, suggesting a possible instability of the TDDFT response or SCF reference in the presence of state-specific solvent polarization. With externally iterative SS-PCM (EISS-PCM), the calculation instead fails with “Unable to diagonalize A–B” during the TDDFT step.
I previously did the optimization process with LR-PCM approach and it worked fine. Could anyone help me to solve this issue.
I am sharing both input files:
GEOM OPT with EISS_PCM:
$molecule
0 1
H -3.1280200 -2.1697000 -0.0874000
C -3.6353300 -1.2144000 -0.0450500
C -2.8758100 0.0000000 0.0000000
C -3.6353300 1.2144000 0.0450500
H -3.1280200 2.1697000 0.0874000
C -5.0131700 1.2046000 0.0453200
H -5.5509800 2.1471000 0.0828500
C -5.7240100 0.0000000 0.0000000
H -6.8090200 0.0000000 0.0000000
C -5.0131700 -1.2046000 -0.0453200
H -5.5509800 -2.1471000 -0.0828500
C -1.4540200 0.0000000 0.0000000
C -0.6791600 1.2186200 0.0012500
C 0.6791600 1.2186200 -0.0012500
C 1.4540200 0.0000000 0.0000000
C 0.6791600 -1.2186200 0.0012500
C -0.6791600 -1.2186200 -0.0012500
C 2.8758100 0.0000000 0.0000000
C 3.6353300 1.2144000 -0.0450500
C 5.0131700 1.2046000 -0.0453200
C 5.7240100 0.0000000 0.0000000
C 5.0131700 -1.2046000 0.0453200
C 3.6353300 -1.2144000 0.0450500
H -1.1852900 2.1753700 -0.0018800
H 1.1852900 2.1753700 0.0018800
H 1.1852900 -2.1753700 -0.0018800
H -1.1852900 -2.1753700 0.0018800
H 3.1280200 2.1697000 -0.0874000
H 5.5509800 2.1471000 -0.0828500
H 6.8090200 0.0000000 0.0000000
H 5.5509800 -2.1471000 0.0828500
H 3.1280200 -2.1697000 0.0874000
N -0.0004510 -0.0004180 3.0104710
C 0.8034210 1.1410550 2.5655350
C 0.6008560 2.3835730 3.4236770
C 0.5844940 -1.2696120 2.5705030
C 1.7695850 -1.7085140 3.4216130
C -1.3914640 0.1258320 2.5675710
C -2.3663980 -0.6721130 3.4241840
H 0.6001440 1.3747620 1.5048230
H 1.8570400 0.8560040 2.6171830
H -0.4339030 2.7359610 3.4018780
H 1.2345320 3.1999000 3.0652400
H 0.8638930 2.1749400 4.4643570
H 0.8780320 -1.2177920 1.5064370
H -0.1884470 -2.0393930 2.6361370
H 2.5973050 -0.9956660 3.3776900
H 2.1483220 -2.6743240 3.0749820
H 1.4686620 -1.8115980 4.4677900
H -1.4929900 -0.1645390 1.5060640
H -1.6702560 1.1811320 2.6218040
H -2.1589760 -1.7452520 3.3960210
H -3.3902280 -0.5253640 3.0685110
H -2.3127390 -0.3455950 4.4663230
$end

$rem
BASIS 6-31G(d,p)
METHOD CAM-B3LYP
JOB_TYPE sp
CIS_N_ROOTS 3
CIS_SINGLETS TRUE
CIS_TRIPLETS FALSE
RPA TRUE
CIS_RELAXED_DENSITY TRUE
CIS_MAX_CYCLES 200
SOLVENT_METHOD PCM
SCF_CONVERGENCE 8
SCF_MAX_CYCLES 200
MEM_TOTAL 248000
MEM_STATIC 4000
$end

$pcm
Theory CPCM
StateSpecific External
LinearResponse false
$end

$solvent
Dielectric 37.5
OpticalDielectric 1.8068
$end

@@@

$molecule
read
$end

$rem
BASIS 6-31G(d,p)
METHOD CAM-B3LYP
JOB_TYPE Optimization
GEOM_OPT_MAX_CYCLES 200
CIS_N_ROOTS 3
CIS_SINGLETS TRUE
CIS_TRIPLETS FALSE
RPA TRUE
CIS_STATE_DERIV 1
CIS_RELAXED_DENSITY TRUE
CIS_MAX_CYCLES 200
SOLVENT_METHOD PCM
SCF_CONVERGENCE 8
SCF_MAX_CYCLES 200
MEM_TOTAL 248000
MEM_STATIC 4000
$end

$pcm
Theory CPCM
StateSpecific External
EqSolv 15
EqState 1
EqState_Follow true
LinearResponse false
$end

$solvent
Dielectric 37.5
OpticalDielectric 1.8068
$end
GEOM OPT with IISS_PCM:
$molecule
0 1
H -3.1280200 -2.1697000 -0.0874000
C -3.6353300 -1.2144000 -0.0450500
C -2.8758100 0.0000000 0.0000000
C -3.6353300 1.2144000 0.0450500
H -3.1280200 2.1697000 0.0874000
C -5.0131700 1.2046000 0.0453200
H -5.5509800 2.1471000 0.0828500
C -5.7240100 0.0000000 0.0000000
H -6.8090200 0.0000000 0.0000000
C -5.0131700 -1.2046000 -0.0453200
H -5.5509800 -2.1471000 -0.0828500
C -1.4540200 0.0000000 0.0000000
C -0.6791600 1.2186200 0.0012500
C 0.6791600 1.2186200 -0.0012500
C 1.4540200 0.0000000 0.0000000
C 0.6791600 -1.2186200 0.0012500
C -0.6791600 -1.2186200 -0.0012500
C 2.8758100 0.0000000 0.0000000
C 3.6353300 1.2144000 -0.0450500
C 5.0131700 1.2046000 -0.0453200
C 5.7240100 0.0000000 0.0000000
C 5.0131700 -1.2046000 0.0453200
C 3.6353300 -1.2144000 0.0450500
H -1.1852900 2.1753700 -0.0018800
H 1.1852900 2.1753700 0.0018800
H 1.1852900 -2.1753700 -0.0018800
H -1.1852900 -2.1753700 0.0018800
H 3.1280200 2.1697000 -0.0874000
H 5.5509800 2.1471000 -0.0828500
H 6.8090200 0.0000000 0.0000000
H 5.5509800 -2.1471000 0.0828500
H 3.1280200 -2.1697000 0.0874000
N -0.0004510 -0.0004180 3.0104710
C 0.8034210 1.1410550 2.5655350
C 0.6008560 2.3835730 3.4236770
C 0.5844940 -1.2696120 2.5705030
C 1.7695850 -1.7085140 3.4216130
C -1.3914640 0.1258320 2.5675710
C -2.3663980 -0.6721130 3.4241840
H 0.6001440 1.3747620 1.5048230
H 1.8570400 0.8560040 2.6171830
H -0.4339030 2.7359610 3.4018780
H 1.2345320 3.1999000 3.0652400
H 0.8638930 2.1749400 4.4643570
H 0.8780320 -1.2177920 1.5064370
H -0.1884470 -2.0393930 2.6361370
H 2.5973050 -0.9956660 3.3776900
H 2.1483220 -2.6743240 3.0749820
H 1.4686620 -1.8115980 4.4677900
H -1.4929900 -0.1645390 1.5060640
H -1.6702560 1.1811320 2.6218040
H -2.1589760 -1.7452520 3.3960210
H -3.3902280 -0.5253640 3.0685110
H -2.3127390 -0.3455950 4.4663230
$end

$rem
BASIS 6-31G(d,p)
METHOD CAM-B3LYP
JOB_TYPE Optimization
CIS_N_ROOTS 3
CIS_SINGLETS TRUE
CIS_TRIPLETS FALSE
RPA TRUE
CIS_RELAXED_DENSITY TRUE
CIS_MAX_CYCLES 200
CIS_STATE_DERIV 1
SOLVENT_METHOD PCM
SCF_CONVERGENCE 8
SCF_MAX_CYCLES 200
MEM_TOTAL 248000
MEM_STATIC 4000
$end

$pcm
Theory CPCM
StateSpecific Internal
ChargeSeparation MARCUS
InternalIteration AEM(f)
EqSolv 15
EqState 1
EqState_Follow true
EqS_Conv 4
LinearResponse false
$end

$solvent
Dielectric 37.5
OpticalDielectric 1.8068
$end

ROHF energy discrepancy between Q-Chem and CFOUR

@juanes Juan Esteban Arias-Martinez — Tue, 24 Feb 2026 22:13:53 +0000

I ran into this issue some time ago… If you input geometries in Bohr with INPUT = BOHR in QChem and the corresponding keyword in CFour they’ll both give you much closer nuclear repulsion energies (but still not exactly the same). So, when one of the programs converts the coordinates to one unit system to the other there is a discrepancy somewhere.

ROHF energy discrepancy between Q-Chem and CFOUR

@Ainosya — Tue, 24 Feb 2026 19:38:15 +0000

Hello,

I agree. However, if one look to the full ZMAT (CFOUR) input,
the geometries are the same

PES of W20 DIANION
O                  0.81970390    3.76180188    1.46198421
H                  1.25733314    3.57623864    0.60662586
H                  1.28053058    3.15236640    2.08985186
O                  3.23531149    0.32384416    0.82599793
H                  2.28704679    0.24534129    0.54501863
H                  3.49730856   -0.60763578    1.01618688
O                  2.12038214    1.83018807    3.06713251
H                  2.71678728    1.43075505    2.40256623
H                  1.39368615    1.16573414    3.09435004
O                  1.67889978    2.66759777   -1.09845507
H                  1.31345759    1.81126453   -0.75488271
H                  0.97978370    2.95012344   -1.72374558
O                  4.03170854    1.18133322   -1.78319056
H                  3.32970052    1.86297519   -1.75980377
H                  3.97661340    0.83597026   -0.86530409
O                 -0.95148381    2.86761049   -2.33075086
H                 -1.07366672    2.76925194   -1.36379456
H                 -0.72502626    1.94837269   -2.61441428
O                  2.44423083   -0.83761865   -3.02570310
H                  3.05470385   -0.16291434   -2.64493233
H                  2.25681964   -1.43877987   -2.27814630
O                 -0.16320877    0.18675191   -2.66773044
H                  0.75486481   -0.07288729   -2.93729087
H                 -0.14033978    0.07651131   -1.66791290
O                 -1.40160789    2.29458293    0.60787206
H                 -0.93199048    1.42618076    0.40724019
H                 -0.68720703    2.86686792    1.00101251
O                  3.69931899   -2.47696211    1.11052040
H                  3.13116201   -2.68488228    1.87264116
H                  3.07256270   -2.57733255    0.36267269
O                 -2.44423083    0.83761865    3.02570310
H                 -3.05470385    0.16291434    2.64493233
H                 -2.25681964    1.43877987    2.27814630
O                  0.95148381   -2.86761049    2.33075086
H                  1.07366672   -2.76925194    1.36379456
H                  0.72502626   -1.94837269    2.61441428
O                  0.16320877   -0.18675191    2.66773044
H                 -0.75486481    0.07288729    2.93729087
H                  0.14033978   -0.07651131    1.66791290
O                 -3.69931899    2.47696211   -1.11052040
H                 -3.13116201    2.68488228   -1.87264116
H                 -3.07256270    2.57733255   -0.36267269
O                  1.40160789   -2.29458293   -0.60787206
H                  0.93199048   -1.42618076   -0.40724019
H                  0.68720703   -2.86686792   -1.00101251
O                 -4.03170854   -1.18133322    1.78319056
H                 -3.32970052   -1.86297519    1.75980377
H                 -3.97661340   -0.83597026    0.86530409
O                 -1.67889978   -2.66759777    1.09845507
H                 -1.31345759   -1.81126453    0.75488271
H                 -0.97978370   -2.95012344    1.72374558
O                 -3.23531149   -0.32384416   -0.82599793
H                 -2.28704679   -0.24534129   -0.54501863                                                                                                                                                                                                                                                                  
H                 -3.49730856    0.60763578   -1.01618688
O                 -0.81970390   -3.76180188   -1.46198421
H                 -1.25733314   -3.57623864   -0.60662586
H                 -1.28053058   -3.15236640   -2.08985186
O                 -2.12038214   -1.83018807   -3.06713251
H                 -2.71678728   -1.43075505   -2.40256623
H                 -1.39368615   -1.16573414   -3.09435004

*CFOUR(CALC=MP2
EXCITE=EOMEE
ESTATE_CONV=7
ABCDTYPE=AOBASIS
ESTATE_SYM=3/3
BASIS=SPECIAL
REF=ROHF
COORD=CARTESIAN
SCF_MAXCYC=1050
GUESS=MOREAD
FROZEN_CORE=ON
MEMORY=100000, MEM_UNIT=MB
SUBGROUP=4
UNITS=ANGSTROM
OCCUPATION=51-50/51-50
SCF_DAMPING=500
SCF_EXPORDER=25
CHARGE=-2
MULTIPLICITY=1)

ROHF energy discrepancy between Q-Chem and CFOUR

@jherbert John Herbert — Tue, 24 Feb 2026 18:26:27 +0000

A discrepancy in the nuclear repulsion energy suggests the geometries aren’t the same.

ROHF energy discrepancy between Q-Chem and CFOUR

@Ainosya — Tue, 24 Feb 2026 18:04:08 +0000

Hello,

I am running a simple ROHF calculation on the W20 dianion using the 6-311++G**+H(s) basis set to follow with a EOM-EE-MP2 job
Using the attached input file, Q-Chem gives the following results:

Nuclear Repulsion Energy = 2353.0399823917 hartrees
E(SCF) =  -1521.10032860

However, using the same basis set and coordinates in CFOUR, I obtain:

NUCLEAR REPULSION ENERGY: 2353.0394897083 a.u.
E(ROHF) = -1521.10034092542673

I am a bit confused, since both calculations were run in the correct Ci symmetry, and in Q-Chem I set unrestricted = false to enforce ROHF. I initially thought the discrepancy might be due to using a contracted basis set in Q-Chem, but using the uncontracted version leads to the same discrepancy.
I also don’t believe the issue is how I massage the SCF procedure in CFOUR, since the discrepancy appears even in the nuclear repulsion energy.

Thank you for your help!

Q-chem input

$molecule                                                                                                                                                                                                                                                                                                                  
   -2 1
O                  0.81970390    3.76180188    1.46198421
H                  1.25733314    3.57623864    0.60662586
H                  1.28053058    3.15236640    2.08985186
O                  3.23531149    0.32384416    0.82599793
H                  2.28704679    0.24534129    0.54501863
H                  3.49730856   -0.60763578    1.01618688
O                  2.12038214    1.83018807    3.06713251
H                  2.71678728    1.43075505    2.40256623
H                  1.39368615    1.16573414    3.09435004
O                  1.67889978    2.66759777   -1.09845507
H                  1.31345759    1.81126453   -0.75488271
H                  0.97978370    2.95012344   -1.72374558
O                  4.03170854    1.18133322   -1.78319056
H                  3.32970052    1.86297519   -1.75980377
H                  3.97661340    0.83597026   -0.86530409
O                 -0.95148381    2.86761049   -2.33075086
H                 -1.07366672    2.76925194   -1.36379456
H                 -0.72502626    1.94837269   -2.61441428
O                  2.44423083   -0.83761865   -3.02570310
H                  3.05470385   -0.16291434   -2.64493233
H                  2.25681964   -1.43877987   -2.27814630
O                 -0.16320877    0.18675191   -2.66773044
H                  0.75486481   -0.07288729   -2.93729087
H                 -0.14033978    0.07651131   -1.66791290
O                 -1.40160789    2.29458293    0.60787206
H                 -0.93199048    1.42618076    0.40724019
H                 -0.68720703    2.86686792    1.00101251
O                  3.69931899   -2.47696211    1.11052040
H                  3.13116201   -2.68488228    1.87264116
H                  3.07256270   -2.57733255    0.36267269
O                 -2.44423083    0.83761865    3.02570310
H                 -3.05470385    0.16291434    2.64493233
H                 -2.25681964    1.43877987    2.27814630
O                  0.95148381   -2.86761049    2.33075086
H                  1.07366672   -2.76925194    1.36379456
H                  0.72502626   -1.94837269    2.61441428
O                  0.16320877   -0.18675191    2.66773044
H                 -0.75486481    0.07288729    2.93729087
H                  0.14033978   -0.07651131    1.66791290
O                 -3.69931899    2.47696211   -1.11052040
H                 -3.13116201    2.68488228   -1.87264116
H                 -3.07256270    2.57733255   -0.36267269
O                  1.40160789   -2.29458293   -0.60787206
H                  0.93199048   -1.42618076   -0.40724019
H                  0.68720703   -2.86686792   -1.00101251
O                 -4.03170854   -1.18133322    1.78319056
H                 -3.32970052   -1.86297519    1.75980377
H                 -3.97661340   -0.83597026    0.86530409
O                 -1.67889978   -2.66759777    1.09845507
H                 -1.31345759   -1.81126453    0.75488271
H                 -0.97978370   -2.95012344    1.72374558
O                 -3.23531149   -0.32384416   -0.82599793
H                 -2.28704679   -0.24534129   -0.54501863
H                 -3.49730856    0.60763578   -1.01618688
O                 -0.81970390   -3.76180188   -1.46198421
H                 -1.25733314   -3.57623864   -0.60662586
H                 -1.28053058   -3.15236640   -2.08985186
O                 -2.12038214   -1.83018807   -3.06713251
H                 -2.71678728   -1.43075505   -2.40256623
H                 -1.39368615   -1.16573414   -3.09435004
$end

$rem
   UNRESTRICTED    FALSE
   METHOD          eom-mp2
   BASIS           gen
   EE_SINGLETS     [6,6]
   EE_TRIPLETS     [6,6]
   SYMMETRY        true
   PURECART        1
  SCF_ALGORROTH    DIIS
  THRESH           14
  S2THRESH         16
$end

$basis
H     0   
S   3   1.00
     33.86500                0.0254938
      5.094790               0.190373
      1.158790               0.852161
S   1   1.00
      0.325840               1.000000
S   1   1.00
      0.102741               1.000000
S   1   1.00
      0.0360000              1.0000000
S   1   1.00
      0.0090000              1.0000000
P   1   1.00
      0.750                  1.000000
****
O     0   
S   6   1.00
   8588.500                  0.00189515
   1297.230                  0.0143859
    299.2960                 0.0707320
     87.37710                0.2400010
     25.67890                0.5947970
      3.740040               0.2808020
SP   3   1.00
     42.11750                0.113889               0.0365114
      9.628370               0.920811               0.237153
      2.853320              -0.00327447             0.819702
SP   1   1.00
      0.905661               1.000000               1.000000
SP   1   1.00
      0.255611               1.000000               1.000000
SP   1   1.00
      0.0845000              1.0000000              1.0000000
D   1   1.00
      1.292                  1.000000
****
$end

CFOUR input (ZMAT)

*CFOUR(CALC=MP2
EXCITE=EOMEE
ESTATE_CONV=7
ABCDTYPE=AOBASIS
ESTATE_SYM=3/3
BASIS=SPECIAL
REF=ROHF
COORD=CARTESIAN
SCF_MAXCYC=1050
FROZEN_CORE=ON
MEMORY=100000, MEM_UNIT=MB
SUBGROUP=4
UNITS=ANGSTROM
OCCUPATION=51-50/51-50
SCF_DAMPING=500
SCF_EXPORDER=25
CHARGE=-2
MULTIPLICITY=1)

CFOUR input (GENBAS)

H:6-311++G**                                                                                                                                                                                 
VTZ Valence Triple Zeta: 3 Funct.'s/Valence AO with diffuse+polarization on all atoms

  2
    0    1   
    5    1   
    7    1   

33.86500 5.094790 1.158790 0.325840 0.102741 0.0360000 0.009

0.0254938 0.00000000 0.00000000 0.00000000  0.00000 
0.190373 0.00000000 0.00000000 0.00000000   0.00000
0.852161 0.00000000 0.00000000 0.00000000   0.00000 
0.00000000 1.000000 0.00000000 0.00000000   0.00000 
0.00000000 0.00000000 1.000000 0.00000000   0.00000 
0.00000000 0.00000000 0.00000000 1.0000000  0.00000 
0.00000000 0.00000000 0.00000000 0.0000000  1.00000 

0.750

1.000000 

O:6-311++G**
VTZ Valence Triple Zeta: 3 Funct.'s/Valence AO with diffuse+polarization on all atoms

  3
    0    1    2   
    5    4    1   
   12    6    1   

8588.500 1297.230 299.2960 87.37710 42.11750 
25.67890 9.628370 3.740040 2.853320 0.905661 
0.255611 0.0845000 

0.00189515 0.00000000 0.00000000 0.00000000 0.00000000
0.0143859 0.00000000 0.00000000 0.00000000 0.00000000
0.0707320 0.00000000 0.00000000 0.00000000 0.00000000
0.2400010 0.00000000 0.00000000 0.00000000 0.00000000
0.00000000 0.113889 0.00000000 0.00000000 0.00000000
0.5947970 0.00000000 0.00000000 0.00000000 0.00000000
0.00000000 0.920811 0.00000000 0.00000000 0.00000000
0.2808020 0.00000000 0.00000000 0.00000000 0.00000000
0.00000000 -0.00327447 0.00000000 0.00000000 0.00000000
0.00000000 0.00000000 1.000000 0.00000000 0.00000000
0.00000000 0.00000000 0.00000000 1.000000 0.00000000
0.00000000 0.00000000 0.00000000 0.00000000 1.0000000

42.11750 9.628370 2.853320 0.905661 0.255611 
0.0845000 

0.0365114 0.00000000 0.00000000 0.00000000 
0.237153 0.00000000 0.00000000 0.00000000 
0.819702 0.00000000 0.00000000 0.00000000 
0.00000000 1.000000 0.00000000 0.00000000 
0.00000000 0.00000000 1.000000 0.00000000 
0.00000000 0.00000000 0.00000000 1.0000000 

1.292

1.000000

Thresh/s2thresh 14?

@crinperizer — Tue, 24 Feb 2026 03:06:07 +0000

Thanks for the detailed advice, it is helping a lot as I try to work through this. I did try the DIIS_GDM option and never saw the switchover to GDM at the expected threshold (10^-2).

Today I was able to converge the SCF at this geometry in one of two ways with DIIS:

FBH partitioning, leading to a similar energy and extent of spin contamination (S2 ~ 0.9) as the nearby geometries. Previously, I had issues combining FBH and geometry optimization, but it doesn’t seem to be a problem here. Maybe the issue was motion vs. the reference fragment calculations.
spin-only constraint on the organometallic fragment, leading to a substantially lower energy solution with less spin contamination (S2 ~ 0.75).

For consistency, I will probably pick FBH to preserve continuity with successful scans at different donor-acceptor distances.

Thresh/s2thresh 14?

@jherbert John Herbert — Mon, 23 Feb 2026 23:29:59 +0000

I did not run it to convergence but nothing has changed with CDFT in several releases so this should be available to you also. If CDFT won’t cooperate with FRAGMO, then you could run the latter as a first job (normal DFT, to obtain converged orbitals for the redox state of interest) then read those in for subsequent CDFT job.

Thresh/s2thresh 14?

@crinperizer — Mon, 23 Feb 2026 21:09:24 +0000

Interesting, did it converge? I’m currently running QChem 6.3, which DOE Perlmutter just updated to.

I did try SG-3 and also saw convergence failure. Currently trying the EML(99,590) grid you recommend.

I also tried SCF_GUESS = FRAGMO, but it seems to interact badly with CDFT. The fragment child jobs try to inherit the CDFT parameters and then crash.

$molecule
1 2
--
1 1
C    2.523658627  -3.833545588   2.677943018
H    2.387030887  -4.759711978   2.108653038
C    1.466499097  -2.941024058   3.089813868
H    0.397929477  -3.072299908   2.891973398
C    2.057103837  -1.869558018   3.821709048
H    1.525635557  -1.027212798   4.277524048
C    3.482840987  -2.097177368   3.865301038
H    4.216432007  -1.460596708   4.372945538
C    3.763275817  -3.333763068   3.195936678
H    4.747818637  -3.799431708   3.081170938
C    2.936015657  -0.051612548   1.145687098
H    2.884253157   0.886755512   1.704518088
C    4.151138617  -0.759071708   0.850891358
H    5.159157867  -0.449300038   1.137733788
C    3.803364967  -1.914906788   0.087113828
H    4.497963627  -2.661317628  -0.310858992
C    2.377668007  -1.926792738  -0.074890552
H    1.819536507  -2.685316498  -0.632287592
C    1.825570027  -0.729068458   0.513895408
C    0.432422377  -0.306682328   0.475824558
C   -0.581875253  -1.095752638  -0.117964722
H   -0.335963073  -2.079384528  -0.523902652
C   -1.890327703  -0.625499898  -0.227599112
H   -2.636744943  -1.260179558  -0.694540242
C   -2.234780573   0.655286582   0.240036228
C   -1.249987333   1.413223242   0.887012558
H   -1.467846313   2.397671982   1.301034468
C    0.050430647   0.942131962   1.001067368
H    0.790917427   1.584080772   1.491599948
Co   2.853984087  -1.951632738   1.911216128
N   -3.542756643   1.206089252  -0.029040642
C   -3.810578263   2.581844762   0.481134368
H   -3.051440083   3.261396452   0.086529948
H   -4.791884393   2.907552022   0.106113758
H   -3.812379843   2.591876222   1.584035528
C   -4.681533923   0.307223182   0.294037118
H   -4.588818713  -0.624151538  -0.267118802
H   -4.692159693   0.107905012   1.378380438
H   -5.619519533   0.793697812  -0.019304612
--
0 2
H   -3.518679933   1.338965198  -1.122167042
C   -0.846002513   1.496688632  -2.591419852
C   -0.773793593   2.765271432  -1.964770512
C    0.378821367   0.871789092  -2.941775462
H   -1.700349723   3.296814322  -1.786691552
H    0.373726097  -0.091611858  -3.459194092
C    0.454846357   3.360778542  -1.668692312
C    1.601189767   1.476559742  -2.663433842
H    0.491801017   4.337759442  -1.173511842
H    2.533107277   0.981655882  -2.955681612
C    1.657607967   2.704141322  -1.986709062
H    2.633734877   3.157361582  -1.764584312
C   -2.122322733   0.873965382  -2.868453662
O   -3.207029833   1.349171102  -2.376219052
C   -2.251902823  -0.341592328  -3.744850012
H   -1.865662293  -1.244707138  -3.233678292
H   -3.312868363  -0.498590338  -3.994392002
H   -1.685974823  -0.235373458  -4.688566142
$end

$rem
METHOD       TPSS
MEM_TOTAL    400000
JOBTYPE      sp
BASIS        def2-svp
XC_GRID      2	SG-2
SCF_CONVERGENCE 8
SCF_GUESS FRAGMO
SCF_PRINT_FRGM TRUE
MAX_SCF_CYCLES 400
SOLVENT_METHOD   smd
DFT_D        D4
CDFT         true
CDFT_THRESH  8
NO_REORIENT  true
POINT_GROUP_SYMMETRY false
INTEGRAL_SYMMETRY    false
MOLDEN_FORMAT   TRUE
$end

$smx
solvent THF
$end

$cdft
-1.0
1 1 39
0.0
1 1 39 s
$end

with the following message:

Symmetry turned off for PCM/SM12/SMD calculation

 Q-Chem fatal error occurred in module qparser/read_cdft.C, line 43:

 Could not find $cdft section in read_cdft


 Please submit a crash report at q-chem.com/reporter 
 
 

 Q-Chem fatal error occurred in module gesman/frgmchild.C, line 693:

 Error executing Q-Chem for fragment 1

Normal Modes Question

@jherbert John Herbert — Mon, 23 Feb 2026 11:18:05 +0000

Note that you can also set VIBMAN_PRINT = 4 to get Q-Chem to print the Hessian in both Cartesian and mass-weighted Cartesian coordinates, along with some other quantities that are ordinarily suppressed in the output. VIBMAN_PRINT = 6 will print even more info.