Theoretical Investigations of Surface Effects in Solids, Anharmonic Properties of Crystals and Surfaces, and Properties of Semiconductors

一个理论凝聚态物理的研究项目将增加我们对表面物理的知识和理解，晶体和表面的非调和性质，以及半导体的性质。表面物理的研究将包括金属低折射率表面声子色散曲线的理论测定，表面极化子的放大，表面极化子在平行或垂直于样品自由表面的超晶格中的传播，以及准晶体中局域界面和杂质态的性质。对晶体和表面的非调和性质的计算机模拟研究将提供对非调和中所有阶数正确的热力学性质和激发寿命的结果。在实际晶体模型的线性化Peierls Boltzmann方程数值解的基础上，研究介电晶体中的声子输运现象，如声子粘度、导热性和超声衰减。由于晶格非谐性，表面声子的线宽也将被研究。对有界非线性介质的激励和统计力学进行理论研究。对半导体性质的理论研究将集中在激发杂质态的寿命和电子-声子相互作用对硅反转层中杂质态的影响上。本文还将研究补偿半导体中的局域电子态。

A research program in theoretical condensed matter physics which will increase our knowledge and understanding of surface physics, the anharmonic properties of crystals and surfaces, and the properties of semiconductors is planned. The study of surface physics will include theoretical determinations of the dispersion curves for surface phonons on low index surfaces of metals, the amplification of surface polaritons, the propagation of surface polaritons in superlattices layered parallel or perpendicular to the free surface of the sample, and the properties of localized interface and impurity states in quasicrystals. Computer simulation studies of the anharmonic properties of crystals and surfaces 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 linewidths of surface phonons due to lattice anharmonicity will also be investigated. A theoretical effort will be made on the excitations and statistical mechanics of bounded nonlinear media. Theoretical investigations into the properties of semiconductors will focus on the lifetimes of excited impurity states and the effects of electron-phonon interaction on impurity states in silicon inversion layers. Localized electronic states in compensated semiconductors will also be studied.