The long-range interactions of S-state alkali atoms with rare gas and hydrogen atoms

Abstract

The coefficients for the long-range interaction energy expansion for an alkalilike S-state atom with a rare-gas-like S-state atom are evaluated. Proceeding from the results of second-order perturbation theory, we express the multipole interaction energies in terms of series of products of oscillator strength sums. The required alkali sums are calculated from spectral data using hypervirial equations. Rare gas sums are reviewed, and new values of some quadrupole and octupole sums estimated. The theory of asymptotic series is employed to obtain numerical values and associated error bounds for C6, C8, and C10 coefficients for a large number of systems. These results are extensively compared with those of others. In particular, excellent agreement is found with accurate theoretical results for H and Li interactions, and improved agreement is found with Li–rare gas elastic scattering results. Finally, further applications and generalizations are discussed.