STM–AFM image formation on TiO2(1 1 0) 1×1 and 1×2 surfaces

Ultra-soft pseudopotentials plane-wave technique is used to simulate the tip–sample interaction and STM–AFM image formation on TiO2(1 1 0) 1×1 and 1×2 surfaces. It is shown that the strong tip–oxygen chemical interaction determines the main feature of the AFM image formation. By checking the effects of tip-induced surface relaxation, spin polarization, and bias voltage, we show that it should be the significant tip-induced surface relaxation on the 1×1 surface which leads to the too small image corrugation observed experimentally on the 1×1 surface.