Adsorption and Desorption at Surfaces: Dynamics vs. Thermodynamics

We have performed molecular dynamics simulations to compute the surface energies of the Si(111)-2x1, 5x5, 7x7 reconstructions. Using the Stillinger and Weber sup 1 2 and 3- body potentials for silicon we find surface energies of +0.37, +0.77, and +0.54 eV/atom repectively relative to the unreconstructed surface.