Quartet states of He+2

The low lying quartet spectrum of the molecular helium cation is investigated by configuration interaction calculations. Using large Gaussian basis sets, potential energy curves for n4 Sigma+u,g and n4 Piu,g are computed for the states n = 1,...,5. Several of these states lead to equilibrium configurations having rather extended bond lengths and some of them also a relatively large dissociation energy. The spectroscopic properties of these equilibrium configurations are studied. Quartet He+2 is most strongly bound in its lowest state 14 Sigmau with Re = 3.424 A and De = 1.348eV.