Excited and core-ionized state calculations with a local potential expressed in terms of the external potential

摘要

A so-called constrained optimized effective potential (COEP) method for excited states (ESs) is briefly reviewed. In contrast to known density functional theory and OEP-based approaches for ESs, the COEP method explicitly introduces orthogonality of the Kohn-Sham (KS) ES function to the lower states of the same symmetry. This makes it possible to solve the KS-like equation so that, "variational collapsing" is avoided and any appropriate local potential can be handled. In particular, we implemented a local effective V _(effr)) expressed as a direct mapping of the external potential, that is, V_(effr)= V_(eff)[V_(ext)(r)]. It is shown that excited and core-ionized states can be treated within the framework of a unified computational approach. Our practical calculations demonstrate that the exchange-only implementation of the COEP method in conjunction with V _(effr) expressed in terms of the external potential is capable of delivering reasonable results on the energies of singly excited as well as core-ionized states and can be easily applied to both atoms and molecules.