[molpro-user] noncanonical orbitals in CCSD-F12

[Kirk Peterson]

Dear Mariusz,

I'm interested in what the real experts have to say, but we have used pseudo-canonical orbitals (from CASSCF) in CCSD-F12 before and they (seem to) work fine. The "trick" is to pass the orbitals through a single iteration of the HF program in order to get some of the information that Molpro requires for F12, e.g.

{multi;canonical,3100.2}
{hf;maxit,1}

I'm not sure if this same procedure is valid for KS orbitals though.

best regards,

-Kirk


On Feb 16, 2013, at 10:44 AM, Mariusz Radon <mariusz.radon at gmail.com> wrote:

> Dear Colleagues:
> 
> Can anyone tell me whether the current implementation of CCSD-F12 in
> Molpro is compatible with use of noncanonical orbitals, in particular
> Kohn-Sham orbitals from preceding DFT calculations?
> 
> Many authors have used KS orbitals in coupled cluster calculations; they
> can often be regarded as a cheap replacement of Brueckner orbitals. In
> Molpro this approach works nice for "ordinary" CCSD, but how about
> explicitly correlated (F12) calculations? Thank you in advance for your
> reply.
> 
> Kind regards,
> Mariusz Radon
> 
> -- 
> Dr Mariusz Radon, Ph.D.
> Coordination Chemistry Group
> Faculty of Chemistry
> Jagiellonian University
> ul. Ingardena 3, 30-060 Krakow, Poland
> http://www.chemia.uj.edu.pl/~mradon
> 
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