[molpro-user] core-valence correlation

Kirk Peterson kipeters at wsu.edu
Sun Feb 20 16:49:33 GMT 2011


all you need to do is add a "core" directive to the method that you're using.  This takes as options the number of frozen orbitals in irreps just like "occ" and "closed".  For example if I want to correlate the 1s electrons of N2, which by default has D2h symmetry:

{ccsd(t);core,1,0,0,0,1}    !  here is the default frozen-core in Molpro explicitly given, 1sigma_g and 1sigma_u frozen
{ccsd(t);core}          ! this will correlate these electrons.  Note that missing zeroes are implied.

here is an analogous example for the HCl molecule (C2v sym), but in the core correlation calculation I still leave the Cl 1s frozen since the cc basis sets are not optimized for that:

{ccsd(t);core,2,1,1}    ! default FC with the 1s, 2s, and 2p(x,y,z) electrons of Cl frozen (note that the default core is always specified at the end of the integral output)
{ccsd(t);core,1}           ! only freeze the Cl 1s

hope this helps,


On Feb 19, 2011, at 11:32 AM, Don Aue wrote:

> Can someone point towards the proper input for getting  core-valence 
> correlation instead of frozen core with cc-pwCVnZ basis sets?
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