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David G.
david.grifith@gmail.com

thank you for prompt reply.

Strictly speaking I have already used the following setting:

$CONTRL icut=11 INTTYP=HONDO $END
$SCF DIRSCF=.TRUE. MAXDII=30 FDIFF=.f. $END

and the energy and density errors of one of the scf procedures are as the following:

DIRECT SCF CALCULATION, SCHWRZ=T   FDIFF=F

                                                                             NONZERO    BLOCKS
ITER EX DEM  TOTAL ENERGY      E CHANGE  DENSITY CHANGE    DIIS ERROR      INTEGRALS   SKIPPED
         * * *   INITIATING DIIS PROCEDURE   * * *
  1  0  0 -6318.293008038 -6318.293008038  16.874057280   0.033936892             -1 253644024
  2  1  0 -6318.294422865    -0.001414827   3.414042850   0.002014172             -1 253618487
  3  2  0 -6318.294479580    -0.000056715   1.496379733   0.002124828             -1 253623176
  4  3  0 -6318.294549256    -0.000069677   1.891834693   0.000885264             -1 253622891
  5  4  0 -6318.294584416    -0.000035159   0.559149100   0.000207986             -1 253620301
  6  5  0 -6318.294586242    -0.000001827   0.553632503   0.000127246             -1 253622189
  7  6  0 -6318.294586678    -0.000000436   0.327187758   0.000053581             -1 253622878
  8  7  0 -6318.294586785    -0.000000107   0.110526091   0.000066342             -1 253622412
  9  8  0 -6318.294586860    -0.000000075   0.065027675   0.000018497             -1 253622147
 10  9  0 -6318.294586877    -0.000000018   0.054933155   0.000004938             -1 253622337
 11 10  0 -6318.294586873     0.000000004   0.051449709   0.000003961             -1 253622415
 12 11  0 -6318.294586883    -0.000000011   0.032116478   0.000001336             -1 253622444
 13 12  0 -6318.294586878     0.000000005   0.014416976   0.000001326             -1 253622413
 14 13  0 -6318.294586882    -0.000000004   0.017963579   0.000000746             -1 253622431
 15 14  0 -6318.294586882     0.000000000   0.029253188   0.000000296             -1 253622410
 16 15  0 -6318.294586877     0.000000006   0.047571716   0.000000271             -1 253622356
 17 16  0 -6318.294586878    -0.000000002   0.017608553   0.000000117             -1 253622453
 18 17  0 -6318.294586886    -0.000000008   0.017771178   0.000000407             -1 253622408
 19 18  0 -6318.294586879     0.000000007   0.009235945   0.000000112             -1 253622377
 20 19  0 -6318.294586882    -0.000000002   0.004881919   0.000000117             -1 253622386
 21 20  0 -6318.294586884    -0.000000002   0.008555893   0.000000179             -1 253622389
 22 21  0 -6318.294586880     0.000000005   0.001003955   0.000000115             -1 253622386
 23 22  0 -6318.294586886    -0.000000006   0.001273499   0.000000275             -1 253622384
 24 23  0 -6318.294586877     0.000000008   0.003755976   0.000000252             -1 253622389
 25 24  0 -6318.294586878    -0.000000001   0.002233113   0.000000118             -1 253622391
 26 25  0 -6318.294586878     0.000000000   0.001947346   0.000000111             -1 253622388
 27 26  0 -6318.294586879    -0.000000001   0.000369859   0.000000172             -1 253622393
 28 27  0 -6318.294586886    -0.000000006   0.003189816   0.000000452             -1 253622392
 29 28  0 -6318.294586882     0.000000004   0.000703361   0.000000222             -1 253622389
 30 29  0 -6318.294586881     0.000000000   0.001907654   0.000000115             -1 253622387
 31 30  0 -6318.294586881     0.000000001   0.000790576   0.000000106             -1 253622380
 32 31  0 -6318.294586879     0.000000001   0.000617188   0.000000189             -1 253622381
 33 32  0 -6318.294586880    -0.000000001   0.000166500   0.000000109             -1 253622379
 34 33  0 -6318.294586877     0.000000004   0.000368997   0.000000170             -1 253622381
 35 34  0 -6318.294586881    -0.000000004   0.000245834   0.000000110             -1 253622378
 36 35  0 -6318.294586876     0.000000005   0.000544505   0.000000218             -1 253622378
 37 36  0 -6318.294586879    -0.000000003   0.000476620   0.000000113             -1 253622380
 38 37  0 -6318.294586875     0.000000004   0.000519073   0.000000233             -1 253622378
 39 38  0 -6318.294586886    -0.000000011   0.000457023   0.000000465             -1 253622379
 40 39  0 -6318.294586884     0.000000002   0.000099051   0.000000223             -1 253622378
 41 40  0 -6318.294586881     0.000000003   0.000124343   0.000000167             -1 253622376


as I understand there is no large difference between steps 33 and 41 ! so I prefer to force the code stop at step 33 to reduce the calculation cost. Is it possible to make the FF do it ? does it seem reasonable to do ?

could we adjust the density convergence criteria in FF ?

would increasing NCONV raise the computation cost more than the current duration ?

Many Thanks, David




On Tue Dec 31 '13 1:06pm, Thomas Pijper wrote
---------------------------------------------
>Dear David,

>Such a problem is often solved by tightening a few accuracy parameters. I recommend adding the following options to see if it solves the problem:

>$CONTRL INTTYP=HONDO ICUT=11 $END

>Switching from SOSCF to DIIS may also help.

>By the way, depending on what the calculated wavefunction will be used for, you might want to tighten NCONV to 6 or higher. If you're performing an MP2 calculation, I recommend you select NCONV=7.
>
>
>Kind regards,
>Thom
>
>