On the determination of step energies. Theoretical considerations and application to an anisotropic Kossel model

Steps on surfaces are important in crystal growth theory, as the step free energy determines the two-dimensional nucleation rate, island growth, step flow and spiral growth. In this paper, it is illustrated that in general in lattice models the step energy of a single step cannot be determined directly by counting broken bonds. A new method is proposed that uses the geometry of a step together with the bonding topology, allowing for a straightforward determination of single-step energies for any case. The method is applied to an anisotropic Kossel model.