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Manuscript Title: ROTIONS: a program for the calculation of rotational excitation cross sections in electron-molecular ion collisions.
Authors: I. Rabadan, J. Tennyson
Program title: ROTIONS
Catalogue identifier: ADJA_v1_0
Distribution format: tar.gz
Journal reference: Comput. Phys. Commun. 114(1998)129
Programming language: Fortran.
Computer: Digital 8400 (Columbus).
Operating system: Unix (OSF 1/ UNICOS 8/ AIX 4).
RAM: 3M words
Keywords: Molecular physics, Scattering, Molecule, Rotational excitations, Cross section, Coulomb-born, Approximation, Electron impact.
Classification: 16.5.

Subprograms used:
Cat Id Title Reference
ABNK_v1_0 COULFG CPC 27(1982)147

Nature of problem:
ROTIONS calculates rotational cross sections from body-frame T-martices and Coulomb-Born (CB) approximation for electron-molecular ion collisions.

Solution method:
The body-frame T-matrices are frame transformed into the lab-frame, and the corresponding cross sections obtained. At the same energies, the CB approximation is used to obtain both total and partial rotational cross sections. The low-l partial-wave contribution to the total CB cross section is substituted by the T-matrix cross section [1].

ROTIONS is restricted to the study of linear targets. The CB approximation is only applicable when the target is charged.

Unusual features:
ROTIONS uses the NAG routine D01AKF [3] (not included) to perform a numerical integration.

Running time:
The only part of the program that takes significant time is the calculation of CB cross sections for quadrupole transitions. It can be up to 0.5 s per energy on Columbus.

[1] I. Rabadan, B.K. Sarpal and J. Tennyson, J. Phys. B: At. Mol. Opt. Phys. 31 (1998) 2077.
[2] A.R. Barnett, Comp. Phys. Commun. 27 (1982) 147.
[3] NAG Fortran Library, The Numerical Algorithms Group Ltd. (Oxford: UK) (1996).