Deriving nonequilibrium interface kinetics from variational principles

Nonequilibrium dynamics at interfaces is generally driven by a chemical potential. Here we demonstrate a generic technique to derive the basic equations of motion, boundary conditions and the chemical potential in a consistent way from fundamental variational principles. As a particular example, we consider a solid surface with elastodynamic effects, together with surface energy and tension. We apply the generic results to perform a linear stability analysis of a planar front subjected to uniaxial stress (Asaro-Tiller-Grinfeld instability), here also with surface tension.