Soft versus hard dynamics for field-driven solid-on-solid interfaces

Analytical arguments and dynamic Monte Carlo simulations show that the microscopic structure of field-driven solid-on-solid interfaces depends strongly on the details of the dynamics. For non-conservative dynamics with transition rates that factorize into parts dependent only on the changes in interaction energy and field energy, respectively (soft dynamics), the intrinsic interface width is field independent. For non-factorizing rates, such as the standard Glauber and Metropolis algorithms (hard dynamics), it increases with the field. Consequences for the interface velocity and its anisotropy are discussed.