(0001) and Cr 2 O 3 (0001) surfaces based on low energy electron and surface X-ray diffraction methods. However, the PhD investigation fails to provide definitive evidence for the presence or absence of surface vanadyl (V=O) species associated with atop O atoms on the surface layer of V atoms. Specifically, the best-fit structure does not include these vanadyl species, although an alternative model with similar relaxations but including vanadyl O atoms yields a reliability-factor within the variance of that of the best-fit structure.keywords: surface relaxation; surface structure; vanadium oxide; photoelectron diffraction present address: