Exact eigenvalues, electronic wavefunctions and their derivatives with respect to the internuclear separation for the lowest 20 states of the HeH2+molecule

Abstract

Exact eigenvalues, normalized electronic wavefunctions and their derivatives with respect to the internuclear separation have been calculated for the lowest 20 states 1s sigma , 2s sigma ,...,4f phi of the HeH²⁺ molecule at internuclear separations 0.1(0.1)20, 20(0.2)80 a₀ assuming infinitely massive nuclei. The numerical importance of the correct exponential form of the wavefunctions is emphasized, and the states are unambiguously correlated to their separated-atoms limits. The molecular states 2p sigma , 4f sigma and 4f pi are bound; their equilibrium parameters have been determined.