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348. BIGSTRN: Empirical Force Field Calculations
by Joseph D. Andose, Merck and Co., Inc., Rahway, New
Jersey 07065; Edward M. Engler, IBM, Inc., Yorktown
Heights, New York 10598; and John B. Collins, John P.
Hummel, Kurt Mislow, and Paul V. R. Schleyer,
Department of Chemistry, Princeton University,
Princeton, New Jersey 08540
BIGSTRN is a convenient empirical force field program
dimensioned for a maximum of 100 atoms, containing a
choice of force fields (Allinger or Schleyer-Mislow).
Input to BIGSTRN consists of Cartesian coordinates,
atom type and connectivity of non-hydrogen atoms. The
program will add necessary hydrogens, define all
interactions and minimize the energy of the structure.
Output consists of a strain analysis of the initial and
final structures and a brief description of the
minimization procedure. The Schleyer-Mislow force
field is capable of considering interactions in
saturated hydrocarbons and carbonium ions. The default
force field can handle a much wider range of molecules
containing a variety of functional groups including
saturated carbon and silicon as well as carbonyl and
aryl groups. The exact extent of the capabilities can
be determined from analyzing the CLASSIFY routines. If
BIGSTRN is not parameterized for a particular
interaction, it returns such a message, with the
exception of biphenyl interactions, which the program
cannot correctly handle.
The program minimizes the structure interatively in
four steps: group (e.g., methyl or phenyl) rotation,
group translation, carbon movement, and hydrogen
movement.
SCOORD will transform internal coordinates (bond
lengths, bond angles and dihedral angles) to Cartesian
coordinates in a format suitable for BIGSTRN.
FORTRAN IV (IBM 360/370 H Level)
Lines of Code: 8618
Recommended Citation: K. Mislow et al., QCPE 11, 348
(1978).
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