Electronic structure of rare-earth sesquioxides and oxysulfides

Abstract

Rare-earth sesquioxides R 2 O 3 and oxysulfides R 2 O 2 S ( R = La , Ce, and Pr) have been theoretically investigated by first-principles pseudopotential method based on local density approximation in density functional theory. The structural, electronic, vibrational and dielectric properties of the rare-earth compounds are investigated with rare-earth pseudopotentials with 4f-electrons of rare-earth atoms as core states. Calculated properties related to the ground states appear consistent with the experimental results. The calculation result also indicates a possibility of another phonon mode assignment from Raman spectra of La 2 O 3 . The present work also implies that 4f-states are essential in electronic excitations to explain the variation of photo-absorption and body-color of R 2 O 3 / R 2 O 2 S.