New anionic states of the lithium trimer

Abstract

Anionic states of Li3 were studied theoretically using a full-valence complete active space (CAS) self-consistent field (SCF) approach to explore their potential energy surfaces followed by quadratic configuration interaction with single, double, and approximate triple excitations calculations to more accurately determine relative energies and electron detachment energies. In addition to the known 1Σg+ state, one triplet (3A2′) and two quintet ( 5A1″ and 5A2′) states were found to be relatively low lying and electronically and geometrically stable in D3h geometries. All of these states remain electronically stable in C2v and D∞h geometries. Hence, they are amenable to photoelectron spectroscopy detection. Preliminary CAS SCF results for the valence isoelectronic Na3- are also reported. © 1994 American Institute of Physics.