Long-range dispersion coefficients for Li, Li(+), and Be(+) interacting with the rare gases.

The long-range dispersion coefficients for the ground and excited states of Li, Li(+), and Be(+) interacting with the He, Ne, Ar, Kr, and Xe atoms in their ground states are determined. The variational Hylleraas method is used to determine the necessary lists of multipole matrix elements for He, Li, Li(+), and Be(+), while pseudo-oscillator strength distributions are used for the heavier rare gases. Some single electron calculations using a semiempirical Hamiltonian are also performed for Li and Be(+) and found to give dispersion coefficients in good agreement with the Hylleraas calculations. Polarizabilities are given for some of the Li and Li(+) states and the recommended (7)Li(+) polarizability including both finite-mass and relativistic effects was 0.192 486 a.u. The impact of finite-mass effects upon the dispersion coefficients has been given for some selected interatomic interactions.