Molecular dynamics simulations of CH3 sticking on carbon surfaces

Abstract

Employing both quantum mechanical and empirical force models, we use molecular dynamics simulations to obtain sticking cross sections for CH3 radical chemisorption on unsaturated sites of carbon surfaces. Effects of the local atomic neighborhood on the chemisorption are examined for the comparison of the results with experiments. Our results show that the chemisorption of a CH3 radical onto a dangling bond is highly affected by the neighborhood of the unsaturated carbon atom sites. Notably, sticking cross sections of totally bare dangling bond sites at the surface and sites partly shielded by neighboring methyl groups are observed to differ by two orders of magnitude, (15.3±1.7) Å2 and (0.2±0.1) Å2, respectively. We describe a steering effect which explains the recent experimental observation that the sticking cross section can be larger than the average area per surface site.