Subject: Re: CCL:External fields in Gaussian98

From: [email-masked] (Robert Zalesny)
Date: Mon, 14 Jan 2002 11:36:09 +0100 (MET)

Hi,
Actually I am not very familiar with calculations of the influence
of external electric field on molecules by the use of Gaussian, but
here it is what I can advise you:
* maybe instead of introducing external field as a dipole
  Gaussian put into Hamiltonian term -dipole*Electric field?
  In this way one obtains uniform electric field...
* As a matter of fact the electric field applied as a "sparkles"
  or dipoles (put at the ends of molecule) is not uniform
  To obtain quasi-uniform electric field with the value let us
  say 0.001 you should separate your + and - sparkles by the
distance about 50 Angstroms. In between you will obtain almost
uniform electric field. In between means the distance about 15 A.
* Try to use GAMESS instead of Gaussian - there is also possiblity
  of optimizing the geometry in the field.
* In MOPAC there is possibility of simulating electric field by 
  sparkles.

I hope that my remarks will help you somehow.
Best regards

Zalesny Robert
Undergraduate student
Quantum Chemistry Group
Wroclaw University of Technology
Poland