Re: CCL:How to place a charge using CHARGE keyword in Gaussian98

Dear Bin,
 last time I did use charges (G94), they were
 placed at the point specified in the input (I
 think in units of bohr). Then the molecule gets
 rotated and shifted into the standard orientation.
 If you optimize, your atoms move, but not the
 charge.
 If you want to place the charge at a specific point
 with respect to your molecule, you may add a
 He-atom to your geometry specification, run a
 short calc (e.g. with %kill l301 1; I'm not sure
 about the syntax anymore. It should kill the calc
 after link 301 finishes for the first time.) and convert
 the cartesian coordinates of the dummy to bohrs.
 In order to prevent the center-of-mass shift caused
 by the He, you need to:
 1) Get cartesian coords for your molecule from the
 last "standard orientation" of the optimization.
 2) Add the He in z-matrix style. Use the "no-reorient"
 or "no-symm" options to prevent reorientation of the
 molecule in the next calc (use %kill).
 3) get the cartesian coords of the He, convert them
 to bohrs and use that coordinate for the charge you
 want to place.
 Since I'm somewhat out of practice with Gaussian,
 the actual keywords may differ a little. Sorry for that.
 Stefan
 ______________________________________________________________________
 Dr. Stefan Fau                    |      fau.,at,.qtp.ufl.edu
 University of Florida             |     (352) 392-6714
 Quantum Theory Project
 2341 NPB #92, P.O.Box 117200
 Gainesville, FL 32611-7200