Abstract
The basic aim of the present investigation is to get some insight into the role played by anharmonicity in the energy transport of disordered materials. We consider a harmonically disordered chain with a regular array of quartic nearest-neighbour anharmonicity (‘disordered Fermi-Pasta-Ulam chain’). Several unexpected features have been found. Some of these can be understood intuitively, whereas others remain surprising. For a single local displacement excitation (Q-excitation) we have found a constructive interplay of Anderson localization and a self-trapped localized soliton (ultra-Debye frequency), whereas for a single local momentum excitation (P-excitation) the interplay is conflicting (reduced Anderson localization, decay and boomerang effect of the hypersonic kink solitons). The most amazing feature is the genesis of longliving subsonic solitons, which hints at the possibility of practically unhindered energy propagation in disordered structures.