Gaussian 03 Online Manual
By default, the charges are read from the input stream, one per line, in this format:
x y z charge 0.0 A [ρ B]
where x,y,z are the coordinates in the input orientation (in the units specified by the Units keyword) and defaulting to Angstroms), charge is the charge, 0.0 is a fixed field, and the remaining items are parameters in the following equation for the additional electron repulsive term:
Indicates that the input charges are specified in the standard
orientation rather than the input orientation. Use the %KJob=L301
Link 0 command to quickly determine the standard orientation for a molecule.
Single point energies, optimizations and frequencies. Not valid with semi-empirical methods or PBC.
To perform geometry optimizations in the presence of background charges, you must use Opt=Z-Matrix NoSymm keywords and define the input geometry either in traditional Z-matrix coordinates or symbolic Cartesian coordinates. Here is an example:
# RHF/STO-3G Opt=Z-Matrix Charge NoSymm Water, STO-3G, point charges 0,1 O H 1 R1 H 1 R2 2 A1 Variables: R1=1.0 R2=1.0 A1=105. 2.0 2.0 2.0 1.2 2.0 -2.0 2.0 1.1