With a first-principles-density-functional method, combined with two different pseudopotentials, ideal oxidized and reduced surfaces of tin oxide are studied. The band structures of bulk and the surface systems are calculated and compared. The nature of the surface ${\mathrm{Sn}}^{2+}$ ions, their outward relaxation, associated “dangling bonds” and band gap states are considered. Also ultraviolet optical constants are determined by using the electric dipole approximation with a scissor correction, and noted to agree with experiments. The presence of the surface, and more significantly, its removed bridging oxygen atoms, becomes apparent in a formation of a new absorption feature. This is predicted to cause about 0.7 eV decrease of the absorption edge.

• Received 29 January 2001

DOI:https://doi.org/10.1103/PhysRevB.64.075407