# [molpro-user] A question about density-fitting in SAPT

cong.wang cong.wang at helsinki.fi
Mon May 4 12:55:34 BST 2009

```Dear everyone,

Hello!

I have a question about density-fitting in SAPT in molpro 2006,
according to the manual,
http://www.molpro.net/info/current/doc/manual/node410.html

"For this one may use the input:

{sapt;intermol,ca=\$ca,cb=\$cb,fitlevel=3
dfit,basis_coul=jkfit,basis_exch=jkfit,basis_mp2=mp2fit,cfit_scf=3}
"

Suppose "this one" refer to
http://www.molpro.net/info/current/doc/manual/node407.html

therefore I made such an input
*********************************************************************
r=5.6
geometry={nosym; he1; he2,he1,r}
basis=avqz

!wf records
ca=2101.2
cb=2102.2

!monomer A
dummy,he2
{hf; save,\$ca}
sapt;monomerA

!monomer B
dummy,he1
{hf; start,atdens; save,\$cb}
sapt;monomerB

!interaction contributions
{sapt;intermol,ca=\$ca,cb=\$cb,fitlevel=3
dfit,basis_coul=jkfit,basis_exch=jkfit,basis_mp2=mp2fit,cfit_scf=3}
*********************************************************************

The output tells me

***************************
PROGRAM * SAPT      Authors: A. Hesselmann, G. Jansen, 2003

(Calculation of intermolecular interaction energy contributions
for single-determinant wave-functions)

Monomer A wave function in record             2101.2
Monomer A electrostatic potential in record   1001.3
Monomer B wave function in record             2102.2
Monomer B electrostatic potential in record   1002.3
Overlap matrix in record                      1000.3

Factor for nonlocal exchange:    1.000000
Print factor:   0
Density fitting level:   3
Level of calculation:    3

CPKS solver:    1
CPKS convergence threshold:   0.10000000E-05
CPKS maximumb number of iterations:     50

Occupied space for monomer A:    1
Virtual  space for monomer A:   91

Occupied space for monomer B:    1
Virtual  space for monomer B:   91

Memory available:                             7272627 words
? Error
? The problem occurs in load_basis

ERROR EXIT
CURRENT STACK:      MAIN

*********************************
Seems there's some problem in the JKFIT basis, then, actually what is
"this one" in the manual,  what is the reason for that? how to solve
this problem?

Thank you very much
Best regards
Cong Wang

Department of Chemistry
Laboratory for Instruction in Swedish
University of Helsinki
A.I. Virtanens plats 1
P.O. Box 55
FI-00014 University of Helsinki
FINLAND

```