[molpro-user] CCSD(T) calculation on Cs+ ion

Grant Hill grant.hill at sheffield.ac.uk
Mon Mar 9 09:06:14 GMT 2015

Dear Bhaskar,

> On 9 Mar 2015, at 07:02, bhaskar sharma <bhaskars1984 at gmail.com> wrote:
> There Grant has has suugested to remove the frozen core approximation. I tried to do this by adding the occ and closed keywords. Now I am getting a different error and it is as follows

When using the occ and closed cards for HF you need to specify the orbitals by symmetry irrep. Your current input is forcing all of the occupied orbitals to be A_g symmetry, which means the HF-SCF program is converging to some strange excited state. This probably isn’t what you want.

What I believe you are looking for is adding the core option to your CCSD(T) directive. As an example,


will correlate al of the electrons not replaced by the ECP.

Best wishes,


P.S. For a shorter input, you could use {ccsd(t);core,} but this is less readable if you ever need to revisit your input file.

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