An ab initio study of the field-induced position change of a C-60 molecule adsorbed on a gold tip

Artikel i vetenskaplig tidskrift, 2007

Recent current/voltage (I/V) curve measurements suggest that C-60 molecules deposited in gold nanojunctions change their adsorption configuration when a finite voltage in a two-terminal setting is applied. This is of interest for molecular electronics because a robust molecular transistor could be based on such junctions if the mechanism of the process is understood. We present density functional theory based plane wave calculations, where we studied the energetics of the molecule's adsorption under the influence of an external field. Particular emphasis was placed on investigating a possible lightning rod effect which might explain the switching between configurations found in experiments. We also analyse our results for the adsorption energetics in terms of an electrostatic expression for the total energy, where the dependence of the polarizability of the junction on the position of the C60 molecule was identified as a crucial property for the field-induced change of adsorption site.