Novel surface diffusion characteristics for a robust pentacene derivative on Au(1 1 1) surfaces

Abstract

Molecular dynamics simulations have been performed in both the ab initio and classical mechanics frameworks of 5,6,7-trithiapentacene-13-one (TTPO) molecules on flat Au(111) surfaces. Results show new surface diffusion characteristics including a strong preference for the molecule to align its long axis parallel to the sixfold Au(111) symmetry directions and subsequently diffuse along these close-packed directions, and a calculated activation energy for diffusion of 0.142eV, about four times larger than that for pure pentacene on Au. The temperature-dependent diffusion coefficients were calculated to help quantify the molecular mobility during the experimentally observed process of forming self-assembled monolayers on gold electrodes.