Programs in Physics & Physical Chemistry
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|Manuscript Title: Subroutines for the evaluation of cross sections of one-photon radiative processes occuring in fast-electron H-atom collisions.|
|Authors: A. Dubois, A. Maquet|
|Program title: BREMSS|
|Catalogue identifier: ABTF_v1_0|
Distribution format: gz
|Journal reference: Comput. Phys. Commun. 60(1990)271|
|Programming language: Fortran.|
|Computer: MACINTOSH II.|
|Operating system: DK1-6.0.2.|
|RAM: 10K words|
|Word size: 8|
|Keywords: Atomic physics, Photon, Atom-electron, Collision, Bremsstrahlung radiation, Double differential Cross section, Adaptive gauss-legendre Quadrature.|
Nature of problem:
During a collision event, the coupling of the electron-atom system with the empty modes of the electromagnetic field can lead to the spontaneous emission of bremsstrahlung radiation. The related transistion amplitude is, apart from a multiplicative factor, identical to the free-free transition one. Using the very compact form of this latter, the present routine evaluates the twofold differential bremsstrahlung cross section, i.e. the integration of the transition amplitude over all propagation directions of the outgoing electron.
The numerical integration presents some difficulties due to localized sharp peaks in the integrand. To deal with such problems, we have written a very efficient adaptive Gauss-Legendre quadrature routine.
Low projectile energies and emission of photons with frequency matching atomic excitation frequencies are prohibited.
The adaptive quadrature routine requires full recursivity qualities from the Fortran compiler.
The time required to evaluate a cross section is typically one minute.
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