Ab initio potential energy surface and excited vibrational states for the electronic ground state of Li 2 H

Abstract

A 285-point multi-reference configuration-interaction involving single and double excitations (MRS-DCI) potential energy surface for the electronic ground state of Li2H is determined by using 6-311G (2df, 2pd) basis set. A Simons-Parr-Finlan polynomial expansion is used to fit the discrete surface with a X2 of 4.64 × 10-6. The equilibrium geometry occurs at Re =0.172 nm and <LiHLi =94.10. The dissociation energy for reaction Li2H(2A)⇑ Li2(1⌆g)+H(2S) is 243.910 kJ/mol. and that for reaction Li2H(2A)⇑HLi(1be)+Li(2S) is 106.445 kJ/mol. The inversion barrier height is 50.388 kJ/mol. The vibrational energy levels are calculated using the discrete variable representation (DVR) method.