From: [email-masked] (D. E. Williams)
Date: Tue, 12 Apr 94 14:43:37 -0400

Dear Dr. Molnar:

	Accurate net atomic charges are needed for force fields.  Reliable
net atomic charges can be found by fitting the molecular electric potential
obtained by ab initio quantum mechanical methods.  In addition to charges,
program PDM93 also allows atomic dipoles/quadrupoles, bond dipoles, and
addition of lone pair electron sites if necessary in order to fit the
electric potential.  A particularly useful feature of the program is the
transparent way in which dependency conditions are specified. As distributed
the program can handle 1000 atoms, but this can easily be increased if
necessary.  I append information about this program.

 -Don Williams

Program PDM93, Potential Derived Multipoles
The following is a brief description of this program.

	Molecules interact with each other via their electric potential.
PDM93 finds optimized net atomic charges and other site multipole
representations of the molecular electric potential based on a variety
of models.  The program is easy to use, flexible and powerful.  Results
are obtained in a single iteration and a complete error treatment is
made which includes estimated standard deviation and correlation of
variables.  The program is written in Fortran 77 and runs on Unix,
Vax, and other computers with F77 capability.

Program PDM93 has a unique combination of features:

o  general sites, e.g. united atoms, not necessarily at atomic locations
o  each site may have any combination of monopole, dipole, or quadrupole
o  bond dipole model is supported
o  restricted (along the bond direction) bond dipole model is supported
o  provision for site dipole vectors in sp2 or sp3 directions
o  selected fixed atomic charges
o  selected groups of atoms with fixed charge
o  atomic charge equalities or symmetry relations
o  rotational invariance of site charges
o  provision for optional foreshortening of X-H bonds
o  comparison with Mulliken charges and Mulliken electric potential
o  direct input from Gaussian-92
o  generalized input from other quantum mechanics programs
o  automatic generation of electric potential grid points
o  provision for custom generation of grid points
o  on-line program manual
o  comprehensive examples are provided

	A review of potential-derived charges may be found in Reviews of
Computational Chemistry, Vol. II, pp. 219-271 (1991).  For further
information contact Dr. Donald E. Williams, Department of Chemistry,
University of Louisville, Louisville, Kentucky 40292, USA.

Tel:(502)588-5975 Fax:(502)588-8149 E-mail:[email-masked]
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Ordering information

Program package consisting of manuals, Fortran-77 source files,
and demonstration example files....................................$2,000

Special discount price is available to academic institutions ........$495

Choose the preferred method of shipment:

	Via ftp, purchaser furnishes valid ftp address................n/c

	Via magnetic media, specify type..............................$20
		DC6150 tape cartridge, unix tar format
	or	MP120 tape cartridge (8mm), Vax backup format
	or	9-track 1600 bpi ascii tape
	or	9-track 6250 bpi ascii tape

Make check payable to the University of Louisville.
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