Re: CCL:freezing atoms in g03 optimizations

Hi Joey,
 yes, the modredundant optimization is a good choice. If you have gaussview the
 procedure is pretty symple trhough the reduntant coordinate editor. If you
 are not using gaussview it could be pretty challanging if your sistem is
 rather big. However you have to put your redundant specifications after a
 blank line at the end of the g03 input. If you need to freeze an atom
 coordinate (cartesian) you'll write
 X N0 F
 where N0 is the atom number you want to freeze
 if you want to freeze a bond lenght the syntax will be
 B N1 N2 F
 for an angle
 A N1 N2 N3 F
 and for a dihedral
 D N1 N2 N3 N4 F
 where Nn are the respective atom numbers
 Hope this help
 Alessandro
 Alle 20:51, martedl 1 giugno 2004, Joey Harriman ha scritto:
 > Hi,
 >
 > I am trying to do a geometry optimization on a large system which contains
 > some atoms that are involved in a transition-state structure.  I would like
 > to fix the portion of the molecule with the TS geometry and do an
 > optimization on the rest of the atoms. What is the best method to freeze
 > the TS atoms?  I have been looking at the ModRedundant function, but am
 > unaware of how to create the secondary input after the zmatrix for this.
 > Any help would be greatly appreciated.
 >
 > Thanks in advance,
 >
 > Joe Harriman
 >
 > ----------------------------------
 > Joe Harriman
 > Computational Chemistry
 > University of New Brunswick
 > Room 228
 > Toole Hall
 > s808o|at|unb.ca
 > ----------------------------------
 >
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 --
 Alessandro Contini, Ph.D.
 Istituto di Chimica Organica "Alessandro Marchesini"
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