Dynamic polarizabilities and van der Waals coefficients of the 21Sand 23Smetastable states of helium

Abstract
Dynamic dipole and quadrupole polarizabilities of the 2 1S and 2 3S metastable states of He are calculated using our time-dependent gauge-invariant method and compared with previous theoretical results. Dispersion coefficients for the He(2 S1)-H2 and He(2 3S)-H2 systems, and their dependence on the intramolecular H-H distance are reported.