Interactions between fluctuating steps on vicinal surfaces: Edge energy effects in reconstruction induced faceting

Surface reconstruction can generate effective attractive interactions between steps on vicinal surfaces, leading to the formation of step bunches. Modified repulsive interactions arise from the fluctuations of a step in the asymmetric environment at the edge of the step bunch. These are determined by a mapping to the ground state energy of a quantum particle between two rigid walls in an external field. This yields an edge energy term that controls the dynamics of faceting and causes wider step spacings at the edge of the bunch, in agreement with Monte Carlo simulations.