An ab initio study of the field-induced position change of aC60 molecule adsorbed on a gold tip

Abstract

Recent current/voltage (I/V) curve measurements suggest thatC60 molecules deposited in gold nanojunctions change their adsorption configuration when afinite voltage in a two-terminal setting is applied. This is of interest for molecularelectronics because a robust molecular transistor could be based on such junctions if themechanism of the process is understood. We present density functional theorybased plane wave calculations, where we studied the energetics of the molecule’sadsorption under the influence of an external field. Particular emphasis was placed oninvestigating a possible lightning rod effect which might explain the switchingbetween configurations found in experiments. We also analyse our results for theadsorption energetics in terms of an electrostatic expression for the total energy,where the dependence of the polarizability of the junction on the position of theC60 molecule was identified as a crucial property for the field-induced change of adsorptionsite.