First principle studies on the geometry and electronic structures of the SnO₂(110) surface

The geometry and electronic structures of the SnO₂(110) surface have been investigated by using the first-principle method. Compared to an ideal surface, the five-fold and six-fold Sn atoms at the top layer shift inwards and outwards, respectively. For the surface oxygen atoms, the in-plane oxygen atoms move outwards, while the displacement of bridged oxygen can be neglectable. When the thickness of slab is smaller than 3 nm, the oscillations of surface energy and the displacements of surface atoms as a function of the number of layers are observed. The results of band structure calculations show that the energy bands mainly originated from the 2p_y/2p_z orbitals of the bridged oxygen appear in the bottom of the band gap of bulk. Furthermore, the influences of the surface relaxation on the electronic properties of SnO₂(110) surface are also discussed.