ELECTRONIC LOCAL DENSITY OF STATES FOR THE TiNi(001) SURFACE

Abstract

We present a self-consistent tight-binding calculation of the electronic structure for the (001) surface of TiNi in the CsCl (B2) structure. The results were obtained using a three-center s–p–d orthogonal tight-binding Hamiltonian fitted to first-principles calculations, within the surface Green function matching formalism. We have analyzed the local density of states (LDOS) for cases with Ni or Ti at the surface layer. For the case where Ni is at the atomic surface layer we find that the corresponding LDOS consists predominantly of bonding states, like in the bulk but with a value at EF reduced by 38% with respect to the bulk; for this surface a strong peak in the LDOS was found at -1.4 eV below EF. For the case where Ti is at the atomic surface layer the corresponding LDOS consists mainly of antibonding states, but with a value at EF higher than in the bulk by 30%. Comparatively, the case where Ni is at the surface layer presents lower values of LDOS at EF and d holes with respect to the case where Ti is at the surface layer, and therefore more chemical activity can be expected for the Ti surface.