Understanding atomic-resolved STM images on TiO2(110)-(1 × 1) surface by DFT calculations

We present a combination of experimental STM images and DFT calculations to understand the atomic scale contrast of features found in high-resolution STM images. Simulating different plausible structural models for the tip, we have been able to reproduce various characteristics previously reported in experimental images on TiO2(110)-(1 × 1) under controlled UHV conditions. Our results allow us to determine the influence of different chemical and morphological tip terminations on the atomic-resolution STM images of the TiO2(110)-(1 × 1) surface. The commonest images have been properly explained using standard models for a W tip, either clean or with a single O atom located at the apex. Furthermore, a double transfer of oxygen atoms can account for different types of bizarre atomic-resolution features occasionally seen, and not conclusively interpreted before. Importantly, we discuss how typical point-defects are imaged on this surface by different tips, namely bridging O vacancies and adsorbed OH groups.Financial support from the Spanish CYCIT (MAT2008-1497) and the Ministry of Science and Innovation (CSD2007-41 NANOSELECT) is greatly acknowledged. CSS is grateful to Ministerio de Educación for the AP2005-0433 FPU grant. CG acknowledges financial support by the Spanish Ministerio de Ciencia e Innovacion (grant 2007-0034) and the CSIC JAE-Doc contract under the program 'Junta para la Ampliación de Estudios', co-funded by FSE and the bilateral action CSIC-Czech Academy of Science 2008CZ25. PJ acknowledges the financial support of GAAV under grant no. IAA 100100905 and GA CR grant no. 202/09/0545.Peer reviewe