The variation-perturbation method using finite basis sets is applied to the hydrogen molecular ion H-2(+). Sets of 'pseudostates' consisting of N pairs of effective oscillator strengths and transition energies are determined and tabulations with N = 6, for both parallel and perpendicular electric dipole transitions, are presented over a range of internuclear distances. Various oscillator strength sums, including those involving the logarithms of the transition energies, and Rayleigh-Schrodinger perturbation theoretic expressions are evaluated. In particular, the isotropic and anisotropic components of the dipole-dipole dispersion energy between H-2(+) and each of a number of atoms, H-2, and N-2 are determined using published pseudostates.
