Potential Energy Curves for the Low-Lying Electronic States of KLi with Fock Space Coupled Cluster Method

Abstract

Abstract Accurate potential energy curves (PECs) are obtained for 10 lowest lying electronic states of the KLi molecule. Contrary to the previous studies, the current approach is based on the first-principle calculations with all electrons correlated. The computational scheme used here is based on the multireference coupled cluster theory formulated in the (2,0) sector of the Fock space. The latter sector provides description of the states obtained by attachment of two electrons to the reference system. This makes it possible to adopt the doubly ionized KLi 2+ structure as a reference. The latter has a very concrete advantage in the calculations of the PECs since they dissociate into closed shell fragments (KLi 2 + → K + +Li + ); hence, the restricted Hartree–Fock reference can be used in the whole range of interatomic distances.