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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.
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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).
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FORTRAN 77 (Ryan-McFarland Compiler)
Lines of Code: 1247
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