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625. EHGO: Extended-Hückel-Based Geometry Optimizing
Program
by Kenneth J. Tupper, QCPE, Indiana University,
Bloomington, IN 47405
This program is based on the Extended Hückel system
developed by R. Hoffman et al. known as FORTICON8 (QCPE
344).
To this system were added the nuclear repulsion work
done by A. Anderson and the line optimizer contained in
the program CINMIN (QCPE 389) by M. Fraser and D. M.
Hayes.
The major change which differentiates this system from
its predecessors is that the Slater coefficients on
functions which are used in these calculations are
treated as optimizable parameters.Without the
inclusion of this change, geometry optimization with
Extended Hückel is not successful.
As the system now exists, it contains parameters for
elements C, N, O and H and is currently dimensioned to
handle 50 atoms. With the speeds at which the system
can operate at this level of approximation, it could be
expanded to do calculations on systems containing 500
atoms and yield structural information on molecules of
biological interest.
Lines of Code: 5000
FORTRAN 77 (VAX)
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