Variational calculations of long-range forces

Abstract

The coefficients of the R exp.-4, R exp.-6 and R exp.-8 terms in the series representation of the long range interaction between two atomic systems at separation R are evaluated by a two - centre variational procedure, using highly refined ground state wave functions. Calculations are carried out for all atom - atom and atom - ion pairs drawn from the one- and two - electron systems H, He(+), He, Li(+) and H(-). The values for the R exp.-6 coefficient are in excellent agreement with the values previously derived from oscillator strength data. (Author)