# Subroutines for the evaluation of cross sections of one-photon radiative processes occuring in fast-electron H-atom collisions

## Description

Abstract We propose two distinct fast routines to evaluate the cross sections of the one-photon processes occuring in the course of fast electron-hydrogen atom collisions: free-free transitions observed in the presence of an external laser source and bremsstrahlung. In spite of the presence of the Coulomb Green's function, a very compact and numerically convenient expression of the related amplitude has been derived so that the computations can be performed on a microcomputer. Title of program: FRFRTR Catalogue Id: ABTE_v1_0 Nature of problem In the course of laser-assisted collisions of relatively fast electrons with hydrogen atom, the system can absorbe or emit a photon. Within a perturbative treatment of these free-free transitions, the total amplitude can be expressed, apart from an atomic form factor, in terms of second-order matrix elements containing the Coulomb Green's function. The present set of subroutines is designed to compute exactly these matrix elements which represent the main numerical difficulty and evaluate the cr ... Versions of this program held in the CPC repository in Mendeley Data ABTE_v1_0; FRFRTR; 10.1016/0010-4655(90)90014-R This program has been imported from the CPC Program Library held at Queen's University Belfast (1969-2019)