I am carrying out a project which involves obtaining the RHF result and the integrals for the chromium dimer (Cr2) under Ahlrichs' SV basis. In the literature against which we attempt to benchmark, the Mg core of each Cr is frozen, yielding 30 orbitals and 24 electrons in total. I thus wonder how should I set up in Molpro to get the cores frozen. My guess is that one should first do something like:
basis = SV
{hf
core}
to obtain the occupied orbitals for a dual Mg system under the same geometry as Cr2's, and next freeze these orbitals in Cr2:
{hf
core,a1,a2,...a8}
{fci, dump = name
core,a1,a2,...a8}
But is this correct? If not, what is the correct way to freeze the cores? Thanks for the help in advance!
