THEORETICAL-STUDY OF THE ELECTRONIC-STRUCTURE OF THE SR-2 MOLECULE

The electronic structure of the Sr-2 molecule has been investigated by use of a two-valence-electron pseudopotential, configuration-interact ion calculations with the four active electrons via the CIPSI (configu ration interaction by perturbation of a multiconfiguration wave functi on selected iteratively) algorithm, and addition of a core-polarizatio n potential. Potential-energy curves for the ground and 21 excited sta tes of Sr-2 as well as for the ground state of Sr-2(+) have been deter mined, and subsequent spectroscopic constants have been obtained. Quit e a good agreement with the few available experimental values is displ ayed for the unambiguously assigned states X (1) Sigma(g)(+) A (1) Sig ma(u)(+) of Sr-2 and X (2) Sigma(u)(+) of Sr-2(+), while present predi ctions lead to a different assignment for the observed B (1) Pi(u) sta te which is found to correspond to the adiabatic (3)(1) Pi(u) state.