title: Non-Born-Oppenheimer calculations of the pure vibrational spectrum of HeH+.
abstract: Very accurate calculations of the pure vibrational spectrum of the HeH(+) ion are reported. The method used does not assume the Born-Oppenheimer approximation, and the motion of both the electrons and the nuclei are treated on equal footing. In such an approach the vibrational motion cannot be decoupled from the motion of electrons, and thus the pure vibrational states are calculated as the states of the system with zero total angular momentum. The wave functions of the states are expanded in terms of explicitly correlated Gaussian basis functions multipled by even powers of the internuclear distance. The calculations yielded twelve bound states and corresponding eleven transition energies. Those are compared with the pure vibrational transition energies extracted from the experimental rovibrational spectrum.
authors.affiliation: Department of Chemistry, University of Arizona, Tucson, 85721, USA.
authors.forename: Michele
authors.initials: M
authors.lastname: Pavanello
authors.forename: Sergiy
authors.initials: S
authors.lastname: Bubin
authors.forename: Marcin
authors.initials: M
authors.lastname: Molski
authors.forename: Ludwik
authors.initials: L
authors.lastname: Adamowicz