Hydrogen motion on a Cu surface: A model study of the rate of single and double site-to-site jumps and the role of the motion perpendicular to the surface

Abstract

We use the Miller, Schwartz, and Tromp flux–flux correlation function formula to calculate the rate coefficient for site-to-site hopping by an adsorbed hydrogen atom on Cu(100). We examine several one- and two-dimensional models with a rigid surface. We reach several qualitative conclusions which are relevant to real systems: the motion perpendicular to the surface plays a very important role in determining the site-to-site hopping rate; there is substantial barrier recrossing which makes transition state theory inaccurate; at moderate temperatures multiple jumps become important.