Semiempirical calculation of van der Waals coefficients for alkali-metal and alkaline-earth-metal atoms

Abstract

The van der Waals coefficients, ${C}_{6},{C}_{8},$ and ${C}_{10}$ for the alkali-metal (Li, Na, K, and Rb) and alkaline-earth-metal (Be, Mg, Ca, and Sr) atoms are estimated by a combination of ab initio and semiempirical methods. Polarizabilities and atom-wall coefficients are given as a diagnostic check, and the lowest order nonadiabatic dispersion coefficient, ${D}_{8}$ and the three-body coefficient, ${C}_{9}$ are also presented. The dispersion coefficients are in agreement with the available relativistic many-body perturbation theory calculations. The contribution from the core was included by using constrained sum rules involving the core polarizability and Hartree-Fock expectation values to estimate the f-value distribution.