Posted by Jellby on June 19, 2006 at 11:40:21:
In Reply to: Re: Some questions about molcas's usage posted by Roland Lindh on June 19, 2006 at 08:24:27:
:The electronic term is not explicitly listed but is a part of the electronic energy. If you run the calculation without the external field it is again trivial to figure out the electronic term.
Are you sure? That would be assuming the wavefunction does not change in response to the external field, or if you consider the distortion energy as part of the electronic interaction energy. In other words, I need to partition the energy change due to the external field into two contributions: the energy spent in changing the wavefunction from the unperturbed one, and the pure interaction energy between the molecule and the external field. To calculate this last term, I have to obtain the electric potential and/or field in the positions of the external charges and/or dipoles, and this is what I want to avoid.