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GU: HINT Coordinates / natinc
Maybe I would be out-of-line for some COORD=HINT adepts, but I've found
that natural internal coordinates are very useful for optimizations,
since they usually reduce the number of steps by upto 30%.
I know they are a pain to make, and more so to use in the input, but for
GAMESS these problems are slightly reduced...since I have written a small
utility that will help make an input file for GAMESS (aka a $CONTRL line
for the NZVAR declaration, and a $ZMAT group for all IZMAT's). All you
need to do is to draw a picture of your molecule, and then follow a small
menu to help you make the proper IZMAT's.
The menu is something like :
MENU
0:END
1:stre 2:tors
3:methyl(sp3) X-CH3 4:methylene(sp3) X-CH2-Y
5:methylene(sp2) H-C(=X)-H 6:methyne(sp2) Y-C(=X)-H
7:methyne(sp3) H-C-XYZ 8:amino X-NH2
9:imino X-NH-Y 10:4-ring
11:5-ring 12:6-ring
13:OH-bend X-O-H 14:CH2 on ring X-CH2-Y
15:X=C on ring A-C(=X)-B 16:X=C(-A)-Y
17:two rings in spiro 18:two fused rings
19:C-H bond on two rings
Type the code number
You type the number (e.g. 2 for torsions) and you will be prompted for
the number of the two central atoms in an .xyz file. Natinc.f will then
make all necessary combinations of all torsions about these atoms, and
this based on the bondlengths, which may be looked for automatically, or
checked by the user. Natinc.f is especially useful for stuff like
six-membered rings and such with all kinds of stuff on (-CH3, NH in
ring...).
If you want to have a look at it, just mail me, and I'll (try to) send
three mails, a little script (natinc), a manual with examples (usually
made to keep mmyself aware of what the program does...) natinc.man and
natinc.f, which has been compiled on Dec, IBM RS6k and Sun Solaris...
It is based on some source of cartic.f and maff.f (BRABO program by C.
Van Alsenoy).
Patrick
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Patrick Bultinck Macrocycles Quantum Chemical
Ph. D. Student Calculations
Dept. Inorganic & Physical Chemistry
University of Ghent Tel. Int'l code/32/9/264.44.44
Krijgslaan 281 (S-3) Fax. Int'l code/32/9/264.49.83
9000 Gent E-mail : Patrick.Bultinck@rug.ac.be
Belgium http://allserv.rug.ac.be/~pbultink/
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