Knowledge Bank

The recent formulation and implementation of State Specific Multireference Perturbation $Theory1$ allows for the treatment of dynamic and non-dynamic electron correlation for systems which are too large to be treated by other Multireference methods. It also allows for the treatment of dynamic and non-dynamic electron correlation of states which are inaccessible to single reference methodologies, such as low spin singlets and doublets. This talk will focus on the active space requirements for the accurate computation of $\omega e,\omega exe$ and $\omega eye$ for the low spin doublet states of some simple diatomics. The active space requirements for MRACPF, MRCISD, and MRPT methodologies will be compared.