Determination of the TiO2 (110) (2×3) surface structure via a parametric approach to STM image simulation

Abstract

Scanning tunneling microscopy (STM) image simulations for transition-metal oxide surfaces have been compared to STM images to determine the atomic structure of the ${\mathrm{TiO}}_{2}$ (110) $(2\ifmmode\times\else\texttimes\fi{}3)$ reconstruction. The calculation of simulated image contrast is based on fitting Slater-type orbital functions to first-principles empty state contours for an unreconstructed ${\mathrm{TiO}}_{2}$ (110). The calculations are extended to arbitrary surface structures using a parametric approach. For the case of ${\mathrm{TiO}}_{2}$ (110), simulations of empty conduction-band edge state densities are compared with STM images to distinguish between two possible atomic terminations of the $2\ifmmode\times\else\texttimes\fi{}3$ surface. The method is proposed as a general approach that allows a first-order interpretation of features in STM images of complex oxide surfaces. The structures of these surfaces are often quite complex and exhibit a mixture of ionic and covalent bonding, often making image interpretation difficult.