  We study the relaxation of a thermal grating in multilayer materials with
interface thermal resistances. The analytical development allows for the nu-
merical determination of this thermal property in Approach to Equilibrium
Molecular Dynamics and suggests an experimental setup for its measurement.
Possible non-diffusive effects at the nanoscale are take into consideration by
a non-local formulation of the heat equation. As a case study, we numerically
apply the present approach to silicon grain boundary thermal resistance
