Dresden 2014 – scientific programme

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O: Fachverband Oberflächenphysik

O 77: Focussed Session: Towards a Quantitative Understanding of Complex Adsorption Structures: Surface Science goes Organic III

O 77.11: Talk

Thursday, April 3, 2014, 18:45–19:00, TRE Phy

DFT calculations addressing a possible imaging mechanismin the Scanning Tunneling Hydrogen Microscope — •Uwe Friedel and Axel Gross — Institute of Theoretical Chemistry, Ulm University, D-89069 Ulm, Germany

The Scanning Tunneling Hydrogen Microscope (STHM) [1] can resolve intramolecular structures of adsorbed organic molecules and even produce intermolecular contrast along lines of expected hydrogen bondings. The method does not only work with hydrogen, which gave the method its name, but also with other molecules such as CO and nobel gas atoms. Still, the reasons for the improved contrast in the STHM are not fully understood yet.

This talk will present dispersion corrected DFT calculations (DFT-D3 [2]) addressing the interaction of a CO molecule positioned between a tip and a pentacene molecule. The distance of the CO molecule from the tip has been monitored as a function of its lateral position above the naphthalene molecule. We will discuss whether an explanation based on Tersoff-Hamann theory [3] can be established in order to understand the improved contrast in the STHM.

[1] C. Weiss et al., J. Am. Chem. Soc. 132, 11864 (2010)
[2] S. Grimme et al., J. Chem. Phys. 132, 154104 (2010)
[3] J. Tersoff and D.R. Hamann, Phys. Rev. Lett. 50, 1998 (1983)