THEORETICAL-STUDY OF MANY-BODY EFFECTS IN THE PHOTOELECTRON-SPECTRA OF UNSATURATED-HYDROCARBONS

A theoretical investigation on the core and valence photoelectron spectra of unsaturated hydrocarbons of increasing complexity, ethylene, trans-butadiene, and trans-hexatriene, has been performed in order to analyze the role of the most important many-body effects on the spectral features and the evolution of these effects along the series. The capability of various configuration interaction (CI) schemes to interpret both the core and the valence ionization satellite structures has been pointed out. The 3h-2v(pi)-1p and 2h-1p CI schemes employed, together with an accurate choice of the basis set and the explicit inclusion of the relaxation, has proven to be very useful tools for this kind of study, being sufficiently accurate to explain the most important correlation features and extendible, at the same time, to longer chain systems. (C) 1994 John Wiley & Sons, Inc.