Efield and Raman spectra?

 Dear CCLers
 I would like to use an external electric field while optimising
 molecular geometry and then calculate the Raman spectra under the
 influence of this external field. Since the evaluation of Raman spectra
 itself uses electric fields is this approach valid??
 Replies will be summarised.
 Patrik Johansson
 Materials Physics
 Chalmers University of Technology