On the atomic roughness of solid–vapor interfaces: Significance of many-body interactions

It is traditionally assumed that the pair energies of atoms on the surface are site independent and equal to the pair energy in the bulk of the crystal (constant bond energy approach). We have assumed that the internal energy of an atom, ψ, depends nonlinearly on the number of nearest neighbors n in the form ψ(n)=−(an+bn2), where a and b are material constants that can be evaluated from experimentally determined heats of sublimation and energies...