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229. CLASTR: Monte Carlo Quasi-Classical Trajectory Program
by J. T. Muckerman, Chemistry Department, Brookhaven
National Laboratory, U. S. Atomic Energy Commission,
Upton, Long Island, New York 11973
This program is capable of providing scattering
information on all possible scattering channels which
result from three-atom systems. An example of such a
system would be the scattering of fluorine atoms with
H2 (see reference 1 at the end of this write-up).
The Monte Carlo techniques involved enter into the
program in the original generation of the coordinates
for the incoming atom. Monte Carlo techniques are also
used in deciding the rotational and vibrational phases
in which the target molecule exists initially.
Another major aspect of this system is the choice of a
potential energy surface which describes the three-atom
system (the F + H2, for instance). As the system
presently exists and in the absence of accurate ab
initio potential energy surfaces, a semi-empirical
surface is used. The London-Eyring-Polanyi-Sato (LEPS)
surface with a single adjustable parameter is used
because of the documentation of its usefulness in
activated complex theory (QCT) calculations.
While this system is entirely FORTRAN, the random
number generator is an Assembly language routine and
will have to be replaced when transferring the program
to other computer systems.
The following three articles by the author are
important in understanding and using this system:
1. James T. Muckerman, "Monte Carlo Calculations of
Energy Partitioning and Isotope Effects in
Reactions of Fluorine Atoms with Fluorine Atoms
H2, HD, and D2," J. Chem. Phys., 54, 1155 (1970).
2. James T. Muckerman, "Classical Dyanmics of the
Reaction in Fluorine Atoms with Hydrogen
Molecules. II. Dependence of the Potential Energy
Surface," J. Chem. Phys., 56, 2997 (1972).
3. James T. Muckerman, "Classical Dynamics of the
Reaction of Fluorine Atoms with Hydrogen
Molecules. III. The Hot-Atom Reactions of 18F
with HD," J. Chem. Phys., 57, 3388 (1972).
FORTRAN IV and Compass (1 routine only)
Lines of Code: 780
Recommended Citation: J. T. Muckerman, QCPE 11, 229
(1973).
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