Subject: CASSCF (Gamess-US) Problem

From: "Dr.Tapan K.Ghanty" <[email-masked]>
Date: Thu, 22 Feb 2001 16:27:00 +0530 (IST)

Hi Friends,
While doing (4,4) CASSCF for a 24-atom molecule 
(with 319 basis functions) I encoutered a problem, 
which I guess, due to data size limit or something 
like that in DIRECT ACCESS RECORD files. I am getting
a crazy number for the FROZEN CORE ENERGY (~ -3800.0)
as well as for Total Energy (~-2600.0) . 
Instead of (4,4) CAS if I do (2,2) CAS, 
there is absolutely no problem and it gives realistic values
(with CORE ENERGY ~-2100.0 and Total Energy (~-795.0). 
I could not  sort out why it is giving crazy numbers for (4,4) CAS.
I have changed the default values in $INTGRL, $MCSCF
and $DRT to change the LENGTH OF DIRECT ACCESS RECORD, but
of no use. I am apending part of the output file for the (4,4) 
CAS calculation. 

I would highly appreciate if someone could help me
in fixing this problem.

With thanks

Dr. Tapan K. Ghanty
Theoretical Chemistry Section
Chemistry Division, BARC
Trombay, Mumbai 400 085
India
-----------------------------------------------------------------------
 TOTAL NUMBER OF SHELLS              =  110
 TOTAL NUMBER OF BASIS FUNCTIONS     =  319
 NUMBER OF ELECTRONS                 =  134
 CHARGE OF MOLECULE                  =    1
 STATE MULTIPLICITY                  =    1
          ----------------------
          INTEGRAL INPUT OPTIONS
          ----------------------
 NOPK  =       1 NORDER=       0 SCHWRZ=       T
     -------------------------------
     INTEGRAL TRANSFORMATION OPTIONS
     -------------------------------
     NWORD  =       0     CUTOFF = 1.0E-09
     MPTRAN =       0     DIRTRF =       T
     AOINTS =DUP     

          -----------------
          MCSCF CALCULATION
          -----------------

 ----- NUCLEAR ENERGY ----- =      1350.4559653354

          -----------------------     ----------------------------
          GUGA DISTINCT ROW TABLE     WRITTEN BY B.R.BROOKS,P.SAXE
          -----------------------     ----------------------------

      GROUP=C1           NPRT=       0
       FORS=       T   INTACT=       F
       FOCI=       F   MXNINT=   30000
       SOCI=       F   MXNEME=   30000
     IEXCIT=       0

      -CORE-    -INTERNAL-  -EXTERNAL-
     NFZC=   0   NDOC=   2   NEXT=   0
     NMCC=  65   NAOS=   0   NFZV=   0
                 NBOS=   0
                 NALP=   0
                 NVAL=   2

 THE MAXIMUM ELECTRON EXCITATION WILL BE   4

 SYMMETRIES FOR THE  65 CORE,   4 ACTIVE,   0 EXTERNAL MO-S ARE

 THE DISTINCT ROW TABLE HAS        14 ROWS.
  THE WAVEFUNCTION CONTAINS        20 WALKS (CSF-S).

 TOTAL NUMBER OF INTEGRALS =         73
 NUMBER OF INTEGRALS/GROUP =         73
 NUMBER OF INTEGRAL GROUPS =          1
 MAXIMUM RECORD SIZES ARE    200 FOR UNIT 11     22 FOR UNIT 12  60001 FOR UNIT 15  90001 FOR UNIT 16
 ...... END OF -DRT- GENERATION ...... 

 OPENING FILE MCDIIS WITH      81 LOGICAL RECORDS OF  101761 WORDS
 MCDIIS WILL CONTAIN A MAXIMUM OF    4050 PHYSICAL RECORDS OF LENGTH 2047 WORDS

 EVALUATING EXCHANGE INTEGRALS FOR DIRECT INTEGRAL TRANSFORMATION
 SCHWARZ INEQUALITY OVERHEAD:     36993 INTEGRALS, T=        0.41

          ------------------------------
          CASSCF INTEGRAL TRANSFORMATION
          ------------------------------
 AO INTEGRALS WILL BE CALCULATED IN DIRECT MODE...

          ----- TWO STEPS TRANSFORMATION -----

       # OF WORDS USED      =   33498002
       # OF WORDS AVAILABLE =   39500000
 DIRECT TRANSFORMATION SKIPS AO INTEGRAL STORAGE ON DISK.

 ----- NUCLEAR REPULSION ENERGY =   1350.45596534
 ----- FROZEN CORE ENERGY       =  -3821.59875761

       # OF (PQ|KL) INTEGRALS WRITTEN       2559
       # OF (IJ|KL) INTEGRALS WRITTEN         55
 ..... END OF CAS INTEGRAL TRANSFORMATION .....

 STATE #    1  ENERGY =   -2602.991078052

      CSF      COEF    OCCUPANCY (IGNORING CORE)
      ---      ----    --------- --------- -----
        2   -0.145583  2101
        4    0.275225  2002
        7   -0.144805  2110
        8    0.073186  1210
        9   -0.198873  1111
       10    0.387145  2011
       11   -0.161897  1111
       13    0.434132  1012
       15    0.272289  2020
       16   -0.194622  1120
       17    0.069554  0220
       18    0.431810  1021
       19   -0.218242  0121
       20    0.342394  0022

****************** Following is the result for (2-electron/2-orbital CAS) *********

 STATE #    1  ENERGY =    -795.549847539

      CSF      COEF    OCCUPANCY (IGNORING CORE)
      ---      ----    --------- --------- -----
        1    0.995481  20
        3   -0.094758  02