Influence of van der Waals forces on the adsorption structure of benzene on silicon

TL;DR

This study investigates how van der Waals forces influence benzene adsorption structures on silicon surfaces using density functional theory, highlighting the importance of including vdW interactions for accurate energy predictions.

Contribution

It demonstrates that the vdW-DF functional predicts different adsorption energy preferences compared to traditional GGA functionals for benzene on silicon.

Findings

vdW-DF predicts higher stability for butterfly structure at most coverages

Traditional GGA functionals favor tight-bridge structure

Van der Waals forces significantly affect adsorption energy calculations

Abstract

Two different adsorption configurations of benzene on the Si(001)-(2x1) surface, the tight-bridge and butterfly structures, were studied using density functional theory. Several exchange and correlation functionals were used, including the recently developed vdW-DF functional, which accounts for the effect of van der Waals forces. In contrast to the PBE, revPBE and other GGA functionals, the vdW-DF functional finds that, for most coverages, the adsorption energy of the butterfly structure is greater than that of the tight-bridge structure.