A theoretical study of the molecules BeF and BeF⁺ in their lowest-lying electronic states

Abstract

The two lowest-lying electronic states of the BeF molecule and the four lowest-lying electronic states of the ion BeF⁺ are described theoretically using the multi-reference single and double excitations configuration interaction approach. This description includes the calculation of potential energy curves, dissociation energies, vibrational energies, dipole and transition moment functions, averaged dipole moments, radiative transition probabilities and lifetimes and a whole set of spectroscopic constants. The quality of the results can be assessed, for example, from the computed vibrational spacings for which our values differ by no more than 9 cm^-1 from the experimental data. Of the four states of BeF⁺, here described for the first time, the ground state shows a very deep well; the next two states are very weakly bound and the fourth state is a repulsive one.