A theoretical description of the ionic species BeF2+

The six lowest-lying electronic states of the dication BeF 2+ are described theoretically using the multireference 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, radiative transition probabilities and lifetimes and a whole set of spectroscopic constants. The results can be expected to have the same quality as previous calculations on BeF and BeF + . Of the six states here described for the first time, only the ground state shows a moderately deep well; another one is very weakly bound and the others are repulsive. The binding can be attributed to a charge polarization interaction involving Be 2+ and F and is strengthened by the strong pi -electron donor character of fluorine. This system is more strongly bound than BeH 2+ .