The vibrational levels of the pyromellitic dianhydride-oxydianiline (PMDA-ODA) polyimide have been calculated with the HONDO ab initio molecular orbital program. The calculated infrared active modes of significant intensity have been assigned to the previously observed peaks in the FT-IR spectrum of the polymer. The eigenvectors of these modes have been visually displayed and discussed in connection with a simulated HREELS spectrum. Changes in the mode frequencies and intensities upon formation of a half-sandwich complex composed of a single chromium atom with the PMDA ligand have also been investigated. Such changes are discussed in connection with changes in the observed HREELS experimental spectrum one might expect during the initial stages of formation of the chromium-PMDA-ODA polyimide interface. © 1989, American Chemical Society. All rights reserved.