Electronic structure study of gold selenides

The electronic structures of alpha- and P-gold selenides are studied, alpha - and beta-AuSe are known as mixed valence compounds having linear (AuSe2, Au+) and square-planar (AuSe4, Au3+) units in their structure simultaneousl y. Our EHTB calculations, however, show that the oxidation states of Au in alpha- and beta-AuSe are both close to +1. This is because the frontier orb itals are largely made up of Se p-orbrtals and Au d-orbitals that lie well below the Fermi level. Our results are consistant with the recent X-ray abs orption spectroscopy study on AuSe which show that all Au in the compound e xhibit a monovalent state independent of their chemical environments.