I am currently working with Molpro, to which I am completely new, trying to run some calculations on $\ce{PdO}$. From literature I have gathered that the ground state is given by $^3\Sigma^-$ state, which translates to a $^3A_2$ state in the $C_{2\mathrm{v}}$ point group, or a wave function card {wf,54,4,2,0}
. Moreover, the literature gives a possible active space of ($4a_1$, $2b_1$, $2b_2$, $1a_2$). I now want to run a CASSCF calculation using this active space, but I am not sure how to determine the occupied (OCC
) and closed shell (CLOSED
) orbitals.
How do I determine these values in general?
Edit
So I have been working on this a little more, and maybe I have found an approach that could work. I can run a simple HF calculation and get a set of orbitals whereby Molpro gives me the corresponding IRREPS. In the case for $\ce{PdO}$ I get a set of occupied orbitals ($13a_1$, $7b_1$, $6b_2$, $2a_2$), whereby two are singly occupied. To get my desired active space of ($4a_1$, $2b_1$, $2b_2$, $1a_2$), I would simply have to close orbitals according to ($9a_1$, $5b_1$, $4b_2$, $1a_2$).
Is this a sensible approach?