From:	dew01(-(at)-)xray5.chem.louisville.edu (Donald E. Williams)
Date:	Fri, 17 Jan 1997 17:58:35 -0500
Subject:	Software available for LSQ Fit of ESP

SOFTWARE AVAILABILITY ANNOUNCEMENT

Pdm97, Least-Squares Fitting of the Molecular Electrostatic Potential With
Net Atomic Charges and/or Multipoles

	Reliable net atomic charges/multipoles can be found by fitting the
molecular electric potential with program pdm97.  The program provides a choice
of geodesic(1), Connolly(2), cubic(3), or user specified grid points for the
electric
potential.  The program includes calculation of hyperbolic-restricted charge
magnitudes(4).  In addition to net atomic charges, the program also allows
any combination of atomic dipoles/quadrupoles, bond dipoles, as well as the
addition of lone pair electron sites if required.  The program directly reads
output files from Gaussian-92 and Gaussian-94 programs, and will accept edited
input from any program which produces a molecular electric potential on a
grid.  Program pdm97 is the most complete and versatile software package
available for this type of calculation.
	Molecular interactions occur during host-substrate docking, cluster,
and crystal formation - whenever molecules associate with one another.  The
energy and geometry of molecular association is determined by the force field.
As a component of the force field, an accurate set of net atomic charges is
required.  Or, if higher accuracy is needed, pdm97 can make extensions to
the net atomic charge model in a variety of ways.
	A particularly useful feature of the program is the easy and transparent
way in which fixed charges and charge dependency conditions are specified.  By
specifying appropriate charge dependencies (e.g., equal charges or equal
sums of charges), chemical intuition can assist to produce charges which are
transferable between related types of molecules or molecular ions.  Hyperbolic-
restricted charges are specifically designed to increase charge transferability.
All charge calculation include a complete error treatment with standard
deviations
and correlations between variables.

References

(1) Spackman, M. A., "Potential Derived Charges Using a Geodesic Point
    Selection Scheme", J. Comput. Chem 1996, 17, 1-18
(2) Connolly, M. L., "Solvent-accessible Surfaces of Proteins and Nucleic Acids",
    Science 221, 709-713 (1983)
(3) Williams, D. E., "Net Atomic Charge and Multipole Models for the Ab Initio
    Molecular Electric Potential", Rev. Comp. Chem. 1991, 2, 219-271.
(4) Bayly, C. L.; Cieplak, P.; Cornell, W. D.; Kollman, P. A., "A Well-Behaved
    Electrostatic Potential Based Method Using Charge Restraints for Deriving
    Atomic Charges: The RESP Model", J. Phys. Chem. 1993, 97, 10269-10280.

For further information contact Dr. Donald E. Williams, Department of Chemistry,
University of Louisville, Louisville, Kentucky 40292, USA.

E-mail:dew01(-(at)-)xray5.chem.louisville.edu
Tel:(502)852-5975 Fax:(502)852-8149




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