Elastic scattering of zero-energy electrons by helium atoms

Abstract

Scattering lengths and their reciprocals for elastic collisions between zero-energy electrons and helium atoms have been calculated using Kohn's variational method. The trial function used makes explicit allowance for correlation between the incident electron and the atomic electrons, and is properly antisymmetrized to allow for electron exchange. In addition the trial wave function depends upon three exponential parameters as well as a number of linear parameters. The `best' values obtained are 1.10 a₀ for the scattering length, and (1.11 a₀)^-1 for the reciprocal of the scattering length. Our value for the scattering length is slightly lower than the 1965 experimentally determined value 1.15 a₀ of Golden and Bandel, but is very close to the value 1.097 a₀ calculated by LaBahn and Callaway in 1966.