Bound and quasibound states of He₂H⁺ and He₂D⁺

Abstract

Bound and quasibound states of He₂H⁺ and He₂D⁺ in three dimensions have been computed by use of a time-dependent quantum-mechanical wave packet approach for total angular momentum J=0. Seven bound states were found for He₂H⁺ and 14 for He₂D⁺, as compared to five for both systems by Lee and Secrest (J. Chem. Phys. 1986, 85, 6565). The potential energy surface needed for the dynamical calculation has been computed by carrying out an ab initio calculation with coupled cluster single and double excitations with perturbative triple excitations [CCSD(T)] employing d-aug-cc-PVTZ basis set. A many-body expansion function proposed by Aguado et al. (Comput. Phys. Commun. 1998, 108, 259) was fitted to the ab initio potential energy values and the resulting fit has a root-mean-square deviation of 10.8 meV (0.25 kcal/mol).