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36l. UNICEPP:United Atom Conformational Energy
Program for Peptides
by M. Jean Browman, Antony W. Burgess, Lawrence G. Dunfield, and Shirley M. Rumsey. Write-up by Gerard F. Endres. Submitted by Harold A. Scheraga, Cornell University, Ithaca, New York 14850 UNICEPP is the implementation of an empirical potential energy algorithm for the conformational analysis of polypeptides (L. Dunfield, A. W. Burgess, and H. A. Scheraga, J. Phys. Chem., Submitted, Oct. 1977). It is a modified version of program ECEPP (QCPE 286), which utilizes previously described empirical potential energy functions, energy parameters, and geometric parameters [F. A. Momany, R. F. McGuire, A. W. Burgess, and H. A. Scheraga, J. Phys. Chem., 79, 2361 (1975)]. UNICEPP saves computer time through the "united atom" approximation, in which CH3, CH2, aliphatic CH and aromatic CH groups are treated as single "atoms" in the computation of interatomic interaction energies. Since this approximation in itself does not represent accurately the 1-4 and true 1-5 interactions involving non-polar hydrogen atoms, these are included in bond torsional functions in which nonpolar hydrogens are treated explicitly. The 1-4 interactions are approximated by a one-dimensional Fourier series for each bond about which rotation takes place, and 1-5 interactions by a two-dimensional Fourier series for each coupled pair of such bonds. FORTRAN IV (IBM 370) Lines of Code: 10,037 Recommended Citation: M. J. Browman et al., QCPE 11, 361 (1978). |