Berlin 2015 – scientific programme

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O: Fachverband Oberflächenphysik

O 37: Scanning Probe Techniques

O 37.5: Poster

Tuesday, March 17, 2015, 18:15–21:00, Poster A

Role of orbital structure in High-resolution STM of molecules — •Ondřej Krejčí, Prokop Hapala, Martin Ondráček, and Pavel Jelínek — Institute of Physics , Academy of Sciences of the Czech Republic, Cukrovarnická 10, Prague, 16253, Czech Republic

Recently, we demonstrated that most features visible in high-resolution AFM images of molecules can be explained by simple mechanical model considering relaxation of an atomistic particle attached to the tip. On top of this, we introduced a simple model for calculating STM current considering only inter-atomic hoppings between relaxed atomistic particle and molecule [1]. The simple model is able to reproduce the main characteristics of high-resolution STM maps in close distance regime where the relaxation effects prevail. But since it completely neglects an electronic structure of the scanned sample, it fails at far distances where the electronic structure is dominating in the STM current. In this work, we implemented an efficient method for simulation of the high resolution STM images considering the molecular electronic structure and the atomistic particle relaxation as well. The method is able to reproduce observed contrast in both the close distance and the far distance regimes, including the gradual transition between them. It gives solid theoretical background for better understanding of high-resolution STM experiments. [1]Hapala, P. et al., Phys. Rev. B 90, 085421 (2014).