An ab initio molecular orbital study of the electronic spectrum and dissociation features of Li 2F

Abstract

Ab initio electronic structure calculations have been used to determine spectroscopic constants and bonding features of the best stable triangular and linear conformations of Li 2F. Bonding populations show that the ionic valence bond structure F − Li 2 + is responsible for the ground state X 2 A 1 and the first excited state 1 2 Σ + u . The electronic spectrum of Li 2F has been predicted by MRD–CI calculations. The strongest band corresponding to the first excitation of 1 2 B 2 – X 2 A 1 centers at 1.2361 eV. Broadside dissociation behavior of Li 2F has been investigated by combining CASSCF and VBSCF calculations. A nonadiabatic electron transfer process during the broadside dissociation process was predicted to take place at the Li–F distance of 3.7 Å.