[molpro-user] DFT-SAPT and CCSD-SAPT for homodimers
tania at tiger.chem.uw.edu.pl
Tue Oct 4 11:27:24 CEST 2016
In principle you are right about a waste of time by calculating monomer
properties twice when monomers are identical, Note however that monomers are
usually calculated in a dimer basis (or monomer-plus some functions on another
monomer basis), and in general they are not identical for two reasons: 1)
monomer positions wrt to each other are not equivalent (most cases if monomers
are something more complicated than atoms), 2) even if they are equivalent, for
degenerate MOs (say px and py pair) a transformation would be necessary in order
to obtain properties of the second monomer in a common basis set, what is tricky
in general. Therefore in all programs known to me identical monomers are
calculated twice. It is simpler and safer.
On Mon, 3 Oct 2016, Leonid Shirkov wrote:
> Dear Molpro Authors,
> as I understand, there is no need to calculate the monomer properties
> twice for homodimers.
> Currently there is no way to treat homodimers as a special case, isn't it?
> Implementation of such option in Molpro could reduce the computational
> cost of SAPT for homodimers.
> Molpro-user mailing list
> Molpro-user at molpro.net
Dr. Tatiana Korona http://tiger.chem.uw.edu.pl/staff/tania/index.html
Quantum Chemistry Laboratory, University of Warsaw, Pasteura 1, PL-02-093 Warsaw, POLAND
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