An ab initio study of a field-induced position change of a C60 molecule adsorbed on a gold tip

TL;DR

This study uses density functional theory to investigate how an external electric field can induce a positional change in a C60 molecule adsorbed on a gold tip, shedding light on switching mechanisms relevant for molecular electronics.

Contribution

It provides a detailed theoretical analysis of field-induced adsorption changes in C60 molecules on gold, highlighting the role of polarizability and electrostatic effects in switching behavior.

Findings

Field-induced position change of C60 on gold tip explained by polarizability.

Electrostatic energy analysis reveals key factors for adsorption switching.

Lightning rod effect considered as a possible mechanism.

Abstract

Recent I/V curve measurements suggest that C60 molecules deposited in gold nanojunctions change their adsorption configuration when a finite voltage in a 2-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 the experiments. We also analyze our results for the adsorption energetics in terms of an electrostatic expression for the total energy, where the dependence of the polarizability of thejunction on the position of the C60 molecule was identified as a crucialproperty for the field induced change of adsorption site.