Research will be conducted in theoretical condensed matter physics to increase the knowledge and understanding of the anharmonic properties of crystals and of surface effects in solids. Computer simulation studies of the anharmonic properties of crystals will provide results for thermodynamic properties and excitation lifetimes that are correct to all orders in the anharmonicity. Phonon transport phenomena in dielectric crystals, such as phonon viscosity, thermal conductivity, and ultrasonic attenuation, will be studied on the basis of numerical solutions of the linearized Peierls Boltzmann equation for realistic crystal models. The study of surface effects in solids will include nonperturbative self-consistent calculations of surface phonon dispersion curves for low index surfaces of metals and the amplification of surface plasmon polaritons. The linewidths of surface phonons due to lattice anharmonicity will also be investigated.
