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QCMP047. DEWARPI: A Semiempirical Pi Molecular
Orbital Program
by Michael J. S. Dewar and James M. Ruiz,
Chemistry Department, The University of
Texas, Austin, Texas 78712
DewarPi is a general purpose program that calculates bond lengths, pi and sigma energies, heats of formation, electron densities and ionization potentials of organic molecules and ions. The program is based on the method of Dewar et al. The program can calculate properties for the ground state and the lowest p and p* states of conjugated organic molecules containing C- C, C-N, C-O and C-S bond types. The excited states and radicals are calculated using the "half-electron" method. The program can also calculate relative energies of specified Wheland intermediates derived from neutral pi systems. The Wheland intermediate calculation is done by removing a specified atom from a structure and calculating the pi energy of the remaining system. The number of electrons is increased, decreased, or kept the same in this pi system, depending on whether the intermediate is an anion, cation or radical. Parameters are not available for molecules having N-N, N-S, O-O, O-S or S-S bond types. __________ References: *DewarPi method applied to hydrocarbons: M.J.S. Dewar and T. Morita, J. Am. Chem. Soc., 91, 789 (1969). *DewarPi Method applied to molecules containing nitogen and oxygen: M.J.S. Dewar and T. Morita, J. Am. Chem. Soc., 91, 796 (1969). *Application of the "half-electron" method: M.J.S. Dewar and N. Trinajstic, J. Chem. Soc. A, 1220 (1971). __________ FORTRAN 77 (Ryan-McFarland Compiler) Lines of Code: 1247 |