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495. MOSOL: MOPAC for Solid-State Physics
by James J. P. Stewart, Frank J. Seiler Research
Laboratory, U.S. Air Force Academy, Colorado 80840
MOSOL is designed to handle any crystalline solid
system involving those elements parameterized for the
MNDO (Modified Neglect of Differential Overlap) method.
Currently, these include H, Be, B, C, N, O, F, Al, Si,
P, S, Cl, Ge, Br, Sn, and I. Since MOSOL was designed
to be as similar as possible to MOPAC, most of the
facilities of MOPAC will eventually be made available
in MOSOL. At the present time, only a very limited set
of facilities (such as the basic geometry optimization
and force calculations options) are provided. Other
more time-consuming or computationally difficult
facilities (such as gradient minimization, UHF
calculations and reaction path-following options) are
not yet written.
Since solid-state theory involves many concepts in
physics not present in molecular chemistry, a complete
extra section designed to make use of these concepts
has been written. Facilities provided here include
graphical depiction of band-structure diagrams and the
density of states (limited at present to one-
dimensional systems).
The most frequently used sequence of operations would
involve the following steps:
1. A guessed unit cell and translation vectors
would be geometry optimized. This is a slow
step, and restart facilities are provided.
2. At the energy minimum, the SCF-Fock matrix
and final geometry are output, preparatory to
running the interactive package.
3. The interactive graphics package is run "on-
line" to provide band structures and densities
of states.
There is no restriction on the space-group of the
crystal nor on the point-group of the unit cell. MOSOL
does not use symmetry unless explicitly requested to do
so by the user. Weak intermolecular bonds, such as
exist in crystalline benzene, can be handled, as well
as extended molecular crystals such as diamond and
boron nitride. As MOSOL makes use of the MNDO
Hamiltonian, any types of system for which MNDO works
well will also work well in MOSOL; conversely, any
systems for which MNDO works badly will also work badly
in MOSOL. In particular, the known lack of hydrogen
bonding and excessive long-range repulsion in MNDO will
also be reflected in MOSOL.
NOTE:This system is distributed in VAX COPY
format.
FORTRAN 77
Lines of Code: 11839
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