Krisztián Palotás, Gábor Mándi, László Szunyogh
We introduce an orbital dependent electron tunneling model and implement it within the atom superposition approach for simulating scanning tunneling microscopy (STM) and spectroscopy (STS). Applying our computationally efficient method, we analyze the convergence and the orbital contributions to the tunneling current and the corrugation of constant current STM images above the W(110) surface. In accordance with a previous study, we find corrugation reversals depending on the bias voltage and the tip-sample distance. Explaining this effect, we highlight the role of the real space shape of the orbitals involved in the tunneling. Moreover, we calculate corrugation inversion maps considering different tip models, and find two qualitatively different behaviors based on the tip orbital symmetry. From these maps, we predict corrugation reversals for specific tips even at positive bias voltages at enlarged tip-sample distances compared to those at negative bias.
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http://arxiv.org/abs/1206.6628
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