Interplay of disorder and anharmonicity in heat conduction: Molecular-dynamics study

The main purpose of the present paper is to study the effect of third- and fourth-order anharmonicity on the heat conductivity in the high-temperature (i.e., classical or saturation) regime of disordered systems. We show that the fourth- and third-order contributions, respectively, enhance and lower the conductivity, which can be understood by a strengthening or weakening of the stiffness of the bonds in the system. On comparing the heat conductivity in percolating and compositionally disordered systems, we find that disorder loosening the structure (percolating systems) favors the effect of anharmonicity.