Critical and noncritical roughening of surfaces.

Abstract

The equilibrium roughening of perfect, clean, crystalline surfaces is described in terms of thermally created atomic steps in the frame of a lattice model (loop gas). If the bending energies for convex and concave step corners are different, the ``particle-hole'' symmetry is destroyed and the sharp infinite-order roughening transition disappears. Instead, a rather smooth crossover from a smooth to a rough surface occurs. A simple model illustrates this result, which is expected to be important for the crystal-growth process and for surface-catalytic reactions.