overlap and electrostatic energies

[Tatiana Korona]

On Tue, 3 Apr 2001, Garold Murdachaew wrote:

> Hi,
>
> I am wondering if molpro (or gaussian, etc.) can calculate the overlap
and
> electrostatic energy between charge densities of two different molecules
A
> and B, where the overlap S and the electrostatic energy E are defined as
>
>         S = int dr rho_A(r) rho_B(r)
>
>       E = int dr_1 int dr_2 rho_A(r_1) 1/abs(r_1 - r_2) rho_B(r_2)
>
> The charge densities may be SCF, MP2, etc. densities obtained from
> previous calculations on isolated monomers A, B.
>
> Thanks for your help!
>
> --Garold Murdachaew
>

Hi,

Yes, with the use of the MATROP command, e.g.

A part of input for He--He, R is interatomic distance, an example is for
the SCF electrostatics:

******************************

INR=4/R

! A monomer
int,skip;dummy,he2
scfa=2110.2
hf;save,scfa

matrop
set,scfA,scfa
load,EPOT ! read bare potential
save,EPOT,5703.2,triang ! save bare potential for A
load,DEN,DEN,scfA  ! read SCF density
coul,J,DEN ! do Coulomb operator
add,WA,1,EPOT,2,J ! do effective potential
print,WA
save,WA,5701.2,triang ! save effective potential

int,skip;dummy,he1
scfb=2111.2
hf;save,scfb
! do effective potential for monomer B
matrop
set,scfB,scfb
load,EPOT ! read bare potential
load,DEN,DEN,scfB  ! read SCF density
coul,J,DEN ! do Coulomb operator
add,WB,1,EPOT,2,J ! do effective potential
save,WB,5702.2,triang ! save effective potential

matrop
load,WAA,triang,5701.2 ! effective potential for A
load,WBB,triang,5702.2 ! effective potential for B
load,DENA,DEN,scfA   ! SCF density for A
load,DENB,DEN,scfB   ! SCF density for B
! calculate E(100)pol
load,EPOT ! load bare potential for monomer B
trace,e100B,DENA,EPOT
trace,e100A,DENB,WAA
load,EPOT,triang,5703.2 ! load bare potential for monomer A
trace,e100A1,DENB,EPOT
trace,e100B1,DENA,WBB

e100=INR+e100A+e100B
show,e100
e100=INR+e100A1+e100B1
show,e100 ! should be the same

Best wishes,

Tatiana