Using singular value decomposition for a compact presentation and improved interpretation of the CIS wave functions

The presentation of the wave function corresponding to an individual CIS solution can be dramatically simplified by using the singular value decomposition method: after transformation it contains no more than min(n(occ), n(virt)) excitations, and is dominated by one or a few ones. This should facilitate the interpretations and finding connections with the experimental spectra. (c) 2007 Elsevier B.V. All rights reserved.