Regensburg 2013 – wissenschaftliches Programm

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O: Fachverband Oberflächenphysik

O 44: Scanning Probe Methods I

O 44.10: Vortrag

Mittwoch, 13. März 2013, 12:45–13:00, H33

Efficient orbital dependent STM simulation model — •Gabor Mandi, Laszlo Szunyogh, and Krisztian Palotas — Budapest University of Technology and Economics, Department of Theoretical Physics, Budapest, Hungary

The interplay of experiment and theory is essential for the correct interpretation of experimental scanning tunneling microscopy (STM) results. We propose an orbital dependent tunneling model and implement it within an atom superposition approach for simulating STM [1].

In order to demonstrate the applicability of this method we consider a W(110) surface, and analyze the orbital contributions to the tunneling current and the corrugation of constant current STM images. In accordance with a previous study [2] we find atomic contrast reversal depending on the bias voltage. We analyze this effect depending on the tip-sample distance using different tip models and find two qualitatively different behaviors. As an explanation we highlight the role of the real space shape of the orbitals involved in the tunneling. STM images calculated by our model agree well with Tersoff-Hamann and Bardeen results. The computational efficiency of our model is remarkable as the k-point samplings of the surface and tip Brillouin zones do not affect the computation time, in contrast to the Bardeen method.

This research was supported by the OTKA PD83353, K77771, TAMOP-4.2.2.B-10/1-2010-0009 projects, and a Bolyai Grant.

[1] Palotas et al., arXiv:1206.6628 (2012).

[2] Heinze et al., Phys. Rev. B 58, 16432 (1998).