The two-body dispersion interactions between multipoles of the hydrogen atoms have been worked out using [2,1] and [3,2] Padé approximants and generalized Casimir–Polder integral formulas. Energy coefficients which appear in the expression for the interaction energy of E2 (H–H), obtained up to the term R−16, are in agreement with those of Dalgarno and Meath.

The second order dispersion energy between an interacting hydrogen pair has been evaluated using up to [6,5] Padé approximants for the frequency dependent multipole polarizabiliities of atomic hydrogen, resulting in convergent values of E2(H–H) which are in harmony with earlier accurate calculations.