METHODS AND PROGRAMS IN COLLISIONS OF POSITRONS WITH ATOMS AND MOLECULES

A detailed description is given in this article of methods used by the authors for carrying out accurate calculations of low-energy positron scattering by H, He and H-2 using the Kohn variational method and very flexible trial functions containing Hylleraas-type correlation terms. The article begins by describing the e+He calculation and then passes on to the e+He calculation. Positronium formation in the Ore gap is taken into account in the case of H but not He. The methods necessary to extend these calculations to e+H-2 scattering below the positronium threshold are then described. The article concludes with a brief description of possible future developments.