Dispersion coefficients for interactions between hydrogen and helium atoms with Coulomb and screened Coulomb potentials

We have carried out calculations to investigate Van der Waals two-body dispersion coefficients C 8 , C 10 and C 12 for the H(1s 2 S)–He(1s 2 1 S) system with screened Coulomb interactions in the framework of a powerful computational technique. The dispersion coefficients for different screening parameters ranging from 0 to 1 a −1 0 are reported. In the unscreened case, the C 12 coefficient is reported for the first time in the literature.