[molpro-user] Questions about frozen core in SAPT calculation

[Andreas Hesselmann]

Dear Cong,

The number to be specified in the frozena/b
option is the number of occupied orbitals
excluding the valence orbitals.

The frozen core option will only effect the 2nd
order terms in the density-fitting part of the
SAPT program (and indunction only if SAPT_ICPKS=0).
For the 1st order terms it is important to include
all occupied orbitals, otherwise the interaction energy
will not be very accurate for small distances of the
monomers.

Best wishes,
Andreas






On Saturday 20 February 2010 17:46, cong.wang wrote:
> Dear everyone,
>
>   Hello,
>
>   Excuse me, I have two questions about the frozen core in the SAPT
> calculation in molpro 2009.
>
> (i) in the manual,
> http://www.molpro.net/info/current/doc/manual/node417.html
>   it is said *
>
> *********
>    SAPT_FROZENA*Number of frozen electrons in the response calculations for
> monomer A (default 0) ***************
>   If I understood correctly, it is the number of electrons (number of
> orbital *2 in closed-shell case). But when I do a SAPT for neon dimer,
> setting SAPT_FROZENA=6
>
>   the output file said
>
>
>  Occupied space for monomer A:    5
>  Virtual  space for monomer A:   87
>
>  Occupied space for monomer B:    5
>  Virtual  space for monomer B:   87
>  ? Error
>  ? frozena>noa!
>  ? The problem occurs in sapt_interface
>
>   does it imply the FROZENA actually is the number of orbital to be frozen?
>
>  (ii) I set FROZENA=0,1,2; FROZENB=1, the  E1tot+E2tot  is invariant
> respect with the frozen core set up. Why the frozen core does not change
> the interaction energy?
>
> Here is an input file, if you need any other information, please let me
> known
>
> *************************
> memory,80,m
> symmetry,nosym
> geomtyp=xyz
> geometry={
> 2
> title
> Ne 0. 0. 0.
> Ne 0. 0. 3.0}
>
> basis=avtz
>
> !wf records
> ca=2101.2
> cb=2102.2
>
>
> !monomer A
> dummy,2
> {hf; save,$ca}
> sapt;monomerA
>
> !monomer B
> dummy,1
> {hf; start,atdens; save,$cb}
> sapt;monomerB
>
> !interaction contributions
> {sapt,SAPT_FROZENA=6;intermol,ca=$ca,cb=$cb}
>
> *************************
>
>
> Thank you very much in advance
> Best regards
> Cong Wang
> Ph. D. Student
>
> 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

-- 
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Andreas Hesselmann
Institut für Physikalische und Theoretische Chemie
Universität Erlangen
Egerlandstraße 3
91058 Erlangen / Germany
Phone:  +49 9131/85-25021
E-Mail: andreas.hesselmann at chemie.uni-erlangen.de
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