Noncontact Atomic Force Microscopy - Yale School of Engineering ...

P.II-04
Dynamical simulations of truxene molecules adsorbed on the KBr (001)
surface
Thomas Trevethan 1,2 and Alexander Shluger 2
1 Department of Physics and Astronomy, University College London, London, UK
2 WPI Advanced Institute for Materials Research, Tohoku University, Sendai, Japan.
We present the results of calculations performed to model the dynamical behavior of
truxene derivative molecules adsorbed on the KBr (001) surface, which have been
imaged at room temperature with the NC-AFM with both molecular and atomic
resolution. An atomistic potential model of the system was built from extensive quantum
chemical calculations and used to investigate the room temperature mobility of the
molecules on different surface sites at room temperature using molecular dynamics
simulations. We find a hierarchy of rates of diffusion on different surface structures: the
molecule is highly mobile on the perfect terrace and is bound to, but mobile along, the
perfect monolayer step edge. The molecule is more strongly bound to double layer kinks,
as observed by their immobilization at these sites in the experimental images; however
the binding energies of the molecule on the two different polarity kinks are very similar.
We show using dynamical simulations how one polarity kink results in a much higher
residence time than the other, suggesting the identity of the kinks in the experimental
images and hence of the identity of the sublattice.
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