A THEORETICAL DESCRIPTION OF THE IONIC SPECIES BEF2+

The six lowest-lying electronic states of the dication BeF2+ are descr ibed theoretically using the multi-reference single and double excitat ions configuration interaction approach. This description includes the calculation of potential energy curves, dissociation energies, vibrat ional energies, dipole and transition moment functions, radiative tran sition probabilities and lifetimes and a whole set of spectroscopic co nstants. The results can be expected to have the same quality as previ ous calculations on BeF and BeF+. Of the six states here described for the first time, only the ground state shows a moderately deep well; a nother one is very weakly bound and the others are repulsive. The bind ing can be attributed to a charge polarization interaction involving B e2+ and F and is strengthened by the strong pi-electron donor characte r of fluorine. This system is more strongly bound than BeH2+.