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523. AMPAC:Version for IBM Mainframe Computers
(Version 1.0)
Modified by Lee L. Lynn, Thomas H. Pierce and Charles
H. Reynolds, Computer Applications Research, Rohm and
Haas Company, Spring House, Pennsylvania 19477, after
the Dewar Research Group, Department of Chemistry, The
University of Texas, Austin, Texas 78712 and J.J.P.
Stewart, Seiler Research Labs, U.S. Air Force Academy,
Colorado Springs, Colorado 80840
AMPAC (QCPE 506) is a general-purpose semiempirical
quantum package which encompasses the MINDO/31, MNDO2
and AM13 Hamiltonians. We have converted this program
directly to run on IBM mainframe computers under either
the MVS or VM operating system. In addition to the
source code, sample JCL is provided for compiling,
linking and running AMPAC under MVS. Since AMPAC uses
numerous variables before they are explicitly assigned
a value, they must all be zero at the beginning of the
calculation. Under VM, this can be accomplished by
simply loading the program with the "/CLEAR" option.
Unfortunately, there is no such option under MVS, but
it is possible to clear the memory by using the linkage
editor parameter "SCTR". An example of the use of the
"SCTR" parameter is included in the sample JCL for
compiling AMPAC under MVS.
There are two changes which will be necessary to use
this version of AMPAC at most sites:
1. Subroutine SECOND has been modified to return the
correct CPU time at our installation. This code
will most likely not work at other installations
and will need to be modified accordingly.
2. We have added a checkpoint restart routine so
calculations can be preserved during system
outages. This is also a site-specific routine and
may be replaced or simply removed. (We have
COMMENTED out the two lines in ITER which invoke
check-point restart).
There are two additional subroutines in this version of
AMPAC which do not appear in the original program. The
first, subroutine INTGEO, periodically dumps the
updated geometry to a file during calculations when a
normal geometry optimization is being performed. The
second, subroutine THPOUT, writes a file which is
compatiblewith ourin-housemolecular
graphics/modeling system, MOLY4. This routine has been
left in because we anticipate releasing a version of
MOLY for general use in the near future. If either of
these capabilities are unwanted, they can easily be
removed by deleting the CALL statements in subroutines
FLEPO and WRITE.
We have implemented this program on IBM 4381, 3084 and
3090 computers and have no reason to believe it would
not run on any other IBM mainframes under either MVS or
VM.
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References:
1. R. C. Bingham, M.J.S. Dewar, D. H. Lo, J. Am.
Chem. Soc., 97, 1285, 1294, 1302, 1307 (1975).
2. M.J.S. Dewar and W. Thiel, J. Am. Chem. Soc., 99,
4899, 4907 (1977).
3. M.J.S. Dewar, E. G. Zoebisch, E. F. Healy, J.J.P.
Stewart, J. Am. Chem. Soc., 107, 3902 (1985).
4. T. M. Dyott, A. J. Stuper, G. S. Zander, J. Chem.
Inf. Comput. Sci., 20, 28 (1980).
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FORTRAN (IBM VMS)
Lines of Code: 16,000
NOTE:This system is delivered as 10 separate files
on its own magnetic tape.
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