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Manuscript Title: Molcol: a program for solving atomic and molecular collision problems.
Authors: D.R. Flower, G. Bourhis, J.-M. Launay
Program title: MOLCOL
Catalogue identifier: ADMK_v1_0
Distribution format: tar.gz
Journal reference: Comput. Phys. Commun. 131(2000)187
Programming language: Fortran.
Computer: IBM RS6000, SGI Origin 2000, Sun E6500.
Operating system: UNIX (AIX 3.2.5/IRIX 6.5/SunOS).
RAM: 16M words
Word size: 32
Keywords: Molecular collisions, Rovibrationally inelastic scattering, Elastic, Quantal coupled channels method, Fine structure excitation.
Classification: 16.7.

Nature of problem:
Inelastic scattering between molecules and atoms possessing internal structure is studied in the laboratory and by means of observations of interstellar space. In order to interpret and analyze these measurements and observations, quantal scattering codes are required which compute inelastic cross sections as functions of the barycentric collision energy.

Solution method:
The partial wave expansion (quantal coupled channels) techinque is employed here. The Schrodinger equation is reduced to a set of coupled, first order differential equations, which are solved by numerical integration in the radial variable to obtain scattering matrices and cross sections. The interaction potential must be supplied in a specified functional form. The program uses Lapack and Blas routines (for matrix algebra).

The program treats collisions between two systems of arbitrary angular momenta, j1 and j2, where j=l+s. System 2 may be allocated an additional internal quantum number.

Running time:
On an IBM RS6000 processor, the first test run (Section 4.1) requires 90 s, and the second test run (Section 4.2) requires 60 s.