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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). |