Relaxation Times in an Anharmonic Crystal with Diluted Impurities

Molecular-dynamics calculations performed on a model of a Xe solid with diluted impurities made of I 2 molecules indicate the existence of a crossover energy, below which the time to reach thermodynamic equilibrium increases rapidly. This effect is associated with the existence of long-living out-of-equilibrium states typical of many-degrees-of-freedom Hamiltonian systems at low energies. The possibility of an experimental verification of this effect by laser spectroscopy techniques is also discussed.