February, 27 (2006) at 4pm

Mario de Menech
Max-Planck-Institut for the Physics of Complex Systems

We present a detailed theoretical study of scanning tunneling imaging and spectroscopy of C60 on silver and gold surfaces, motivated by the recent experiments X. Lu et al, PRL 90,096802 (2003), PRB 70,115418 (2004). The surface/sample/tip system is described within a self-consistent Density Functional Theory based on tight-binding model. The topographic and conductance images are computed at constant current from a full self-consistent transport theory based on nonequilibrium Green's functions and compared with those simulated from the local density of states. The molecular orbitals of C60 are clearly identified in the energy resolved maps, in close correspondence with the experimental results. We show how the tip structure and orientation can affect the images. In particular, we consider the effects of truncated tips on the energy resolved maps.