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Manuscript Title: UNIMOL: a program for Monte Carlo simulation of RRKM unimolecular decomposition in molecular beam experiments.
Authors: K. Rynefors
Program title: UNIMOL
Catalogue identifier: AAOA_v1_0
Distribution format: gz
Journal reference: Comput. Phys. Commun. 27(1982)201
Programming language: Fortran.
Computer: IBM 3033N.
Operating system: OS MVS-SP1, JES2.
RAM: 120K words
Word size: 32
Keywords: Unimolecular Decomposition, Rrkm-theory, Transition state, Centrifugal barrier, Angular momentum Conservation, Reaction cross sections, Branching ratio, Monte carlo sampling, Molecular physics, Chemical kinetics.
Classification: 16.12.

Nature of problem:
Reactive and nonreactive absolute angular distributions are measured in crossed molecular beam experiments. Absolute cross sections and branching ratios can be determined in the experiment only with some form of simulation algorithm.

Solution method:
The procedure uses Monte Carlo techniques to simulate the formation and decomposition of the complex. Angular momentum conservation, the simultaneous interaction of several decomposition channels and strict flux conservation are included in the procedure. Three nonstatistical effects, based on trajectory calculations and dynamical arguments, are also considered.

Restrictions:
Only three atomic complexes are considered.

Unusual features:
Three subroutines are used from the IMSL- and Harwell subroutine libraries.

Running time:
Running time is almost proportional to the number of sampled systems. In the test run 80 000 compex forming systems takes about seven minutes on the IBM 3033N.