[molpro-user] Failure in large CASPT2(23,19) run

[H. -J. Werner]

You will hardly be able to do this calculation with 15 active
orbitals. Try to increase closed and use use RS2C rather than RS2. 
In RS2C closed-shell (inactive) orbitals are treated much more
efficiently than in RS2, see Celani and HJW, J. Chem. Phys. {\bf 112}, 5546 (2000)
It is often not a good idea to include very many nearly doubly occupied
orbitals in the active space, since there are too few  weakly occupied 
orbitals to correlate them. This can lead to artifical results. In your case
occ,17;closed,14  seems to be qualitatively correct, and larger spaces
which work are  occ,18;closed,13; or occ,19;closed,12
Best regards
H.-J. Werner
On Mi, 25 Mai 2005, Vadim V. Kislov wrote:

>Dear All, 
>We have encountered a memory problem during of CASPT2(23,15) calculation of C2H3O2 species. We are using a dual Itanum 2 1.5GHz workstation with 8Gb of memory and 8 Gb of swap space.
>
>Input looks like
>
>***,C2H3O2 TS 9
>memory,1000,m;
>file,2,c2h3o2_9.wfu;
>geometry={angstrom;
> c,                   0   ,-0.01897, -0.0666 ,  0.4391
> c,                   0  , -1.36099, -0.18654, -0.11713
> h,                   0  ,  0.05533, -0.03293,  1.51564
> h,                   0  , -2.2241 ,  0.09429,  0.42556
> h,                   0 ,  -1.45278, -0.35638, -1.17026
> o,                   0,    0.50073,  1.0631 , -0.21201
> o,                   0,    0.97344, -0.84162, -0.16122}
>basis=vtz
>int
>!rhf;occ,16;closed,15;wf,31,1,1;
>!mcscf;occ,19;closed,4;wf,31,1,1;orbprint,10;
>rs2;occ,19;closed,4;core,4;wf,31,1,1;
>
>In the end I have the following output:
>
>1PROGRAM * RS2 (Multireference RS Perturbation Theory)     Authors: H.-J. Werner
> (1993), P. Celani (1998)
>
>
> Convergence thresholds:  THRVAR = 1.00D-08  THRDEN = 1.00D-06
>
> Number of optimized states:  1  Roots:   1
> Number of reference states:  1  Roots:   1
>
> Reference symmetry:               1   Doublet
> Maximum shell inside CICON        7
>
> Maximum number of shells reduced from  7 to  6
> Maximum number of spin couplings:    132
>
> Reference space:    71955 conf   305760 CSFs
> N elec internal:    71955 conf   305760 CSFs
> N-1 el internal:   157950 conf  1337700 CSFs
> N-2 el internal:   306735 conf  5245240 CSFs
>Number of electrons in valence space:                     23
> Maximum number of open shell orbitals in reference space:  7
> Maximum number of open shell orbitals in internal spaces: 11
>
>
> Number of core orbitals:           4 (   4 )
> Number of active  orbitals:       15 (  15 )
> Number of external orbitals:     143 ( 143 )
>
> Molecular orbitals read from record     2140.2  Type=MCSCF/NATURAL (state 1.1)
>
> Integral transformation finished. Total CPU:  16.20 sec, npass=  1  Memory used
>:   5.77 MW
>
> Number of p-space configurations:  49
>
> Reference wavefunction optimized for reference space (refopt=1)
>
> State     Reference Energy
>   1        -227.20596745
> Number of blocks in overlap matrix:     2   Smallest eigenvalue:  0.11D-01
> Number of N-2 electron functions:     225
> Number of N-1 electron functions: 1337700
>
> Number of internal configurations:               305760
> Number of singly external configurations:     191291100
> Number of doubly external configurations:       2301585
> Total number of contracted configurations:    193898445
> Total number of uncontracted configurations:53707038840
>
> Weight factors for SA-density in H0:    1.000000
>
> FIMAX=  0.29D+00  FXMAX=  0.11D-04  DIAG=  F  F  NOREF=1  NOINT=0  IHPPD=2
>
> Nuclear energy:                     112.31304506
> Core energy:                       -233.39134100
> Zeroth-order valence energy:        -17.12532307
> Zeroth-order total energy:         -138.20361901
> First-order energy:                 -89.00234844
>
> There are only all-active singles.
> Contracted Singles code is turned off.
>
>
> Using uncontracted singles
>
> noint is 2
>
> Diagonal Coupling coefficients finished.               Storage: 1477293 words,
>CPU-Time:      1.48 seconds.
> Energy denominators for pairs finished in 0 passes.    Storage: 1411722 words,
>CPU-time:      0.00 seconds.
>
>  ITER. STATE  ROOT      NORM       CORR.ENERGY   TOTAL ENERGY   ENERGY CHANGE
>     DEN1      VAR(S)    VAR(P)      TIME
>    1     1     1     1.06866120     0.00000000  -227.20596745     0.00000000
> -0.65884541  0.69D-01  0.11D+00  9509.93
>
>
> Disastrous lack of store, CIGPS
>
>
>
>I was able to run CASPT2 calculations with smaller active space (9,9) where the number of configurations just sligthly smaller. 
>
>
>I will gladly appreciate any suggestions how to override this problem (if possible). Also I would like to know what causes this problem (lack of disk space, memory or system swap). 
>
>Thanks.  
>
>
>Vadim V.Kislov
>Postdoctoral Research Associate,
>Department of Chemistry and Biochemistry,
>Florida International University
>11200 SW 8th Street, Miami, FL 33199
>e-mail: kvv_bne at mail.ru
>tel: 305-348-1945
>

-- 
Prof. Hans-Joachim Werner
Institute for Theoretical Chemistry
University of Stuttgart
Pfaffenwaldring 55
D-70569 Stuttgart, Germany
Tel.: (0049) 711 / 685 4400
Fax.: (0049) 711 / 685 4442
e-mail: werner at theochem.uni-stuttgart.de