Regensburg 2013 – scientific programme

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O: Fachverband Oberflächenphysik

O 45: Metal Substrates II

O 45.8: Talk

Wednesday, March 13, 2013, 12:15–12:30, H42

The study of Pb self-diffusion from first principles — •Xiaohang Lin and Axel Groß — Institute of Theoretical Chemistry, Ulm University, D-89069 Ulm/Germany

With the single-atom transistor [1], the first actively switchable electronic device on the atomic scale was demonstrated. By the controlled relocation of one individual atom within an electrochemically fabricated metallic quantum point contact, an electrical current could be switched on and off. Changes in the atomic-scale structure within the contact area controlled by the electrode potential in an electrochemical set-up result in conductance changes of the atomic-scale contact.

Here, we study atomic-scale relocation processes in contacts form at Pb electrodes with periodic density functional theory (DFT) calculations. It is known that diffusion processes play a crucial role during the atomic-scale deposition and structure formation. For this reason, as a first step barriers for self-diffusion processes have been calculated using automatic transition state search routines. In order to address structured surfaces more realistically, an emphasis has been put on processes near step edges. It turned out that at such edges, two-particle exchange processes are very important for the diffusion in contrast to the “naive” direct single-particle hopping mechanism.

[1] F.-Q. Xie, L. Nittler, Ch. Obermair, Th. Schimmel, Phys. Rev. Lett. 93, 128303 (2004).