The evolution of a crystal surface: Analysis of a one-dimensional step train connecting two facets in the ADL regime

We study the evolution of a monotone step train separating two facets of a crystal surface. The model is one-dimensional and we consider only the attachment–detachment-limited regime. Starting with the well-known ODEs for the velocities of the steps, we consider the system of ODEs giving the evolution of the “discrete slopes.” It is the l2l2-steepest-descent of a certain functional. Using this structure, we prove that the solution exists for all time and is asymptotically self-similar. We also discuss the continuum limit of the discrete self-similar solution, characterizing it variationally, identifying its regularity, and discussing its qualitative behavior. Our approach suggests a PDE for the slope as a function of height and time in the continuum setting. However, existence, uniqueness, and asymptotic self-similarity remain open for the continuum version of the problem.

► We describe the relaxation of a monotone one-dimensional crystal surface in the ADL regime. ► We identify a steepest-descent structure for the system of ODEs for the slope evolution. ► In the discrete setting, the evolution is asymptotically self-similar as t→∞t→∞. ► The continuum self-similar solution is the limit of the discrete self-similar solution as N→∞N→∞. ► We give a detailed analysis of the continuum self-similar solution.