U.S.-Italy Cooperative Research: Theoretical Investigation of the Lattice Dynamics of Clean Surfaces and Surfaces with Adsorbates

该奖项将支持教授理查德沃利斯和阿列克谢 位于欧文的加州大学的Maradudin 研究合作，与教授Escherinio Bortolani的 意大利摩德纳大学。 调查人员打算把重点放在 测量了表面声子的色散曲线， 用于各种金属、绝缘体和半导体， 氦原子非弹性散射技术 他们打算 开展协调一致的理论和计算工作， 提供表面声子线宽的值，作为 铜、银和金表面的温度。 所需的 非谐波参数将从已知的三阶 阶弹性常数 研究人员还打算携带 计算出了表面声子色散曲线， 贵金属表面的本征向量， 面心立方过渡金属 近年来，在实验方面取得了很大进展， 宽谱线表面声子色散曲线的测定 晶体表面的扇形，用非弹性电子散射 氦原子的非弹性散射 后一种技术具有 已成功应用于各种材料， 不断为表面动力学研究提供新的见解。 拟议的合作将使美国调查人员能够 受益于意大利调查人员的专业知识， 计算精确的声子频率和本征向量， 贵金属表面 美方将依次提供其 计算表面声子线宽的专业知识， 这源于他们的综合项目研究， 晶体表面的非谐效应。

This award will support Professors Richard Wallis and Alexei Maradudin of the University of California at Irvine in a research collaboration with Professor Virginio Bortolani of the University of Modena, Italy. The investigators intend to focus on surface phonons, whose dispersion curves have been measured for a wide variety of metals, insulators, and semiconductors by the inelastic helium atom scattering technique. They intend to carry out a concerted theoretical and computational effort to provide values for the surface phonon linewidths as functions of temperature for copper, silver, and gold surfaces. The required anharmonic parameters will be determined from the known third order elastic constants. The researchers also intend to carry out calculations of surface phonon dispersion curves and eigenvectors for surfaces of noble metals and face-centered-cubic transition metals. Much progress has been made in recent years in the experimental determination of surface phonon dispersion curves of a broad fange of crystal surfaces, using inelastic electron scattering and inelastic helium atom scattering. The latter technique has been applied with great success to a wide range of materials and keeps providing new insights into the study of surface dynamics. The proposed collaboration will enable the U.S. investigators to benefit from the expertise of the Italian investigators in calculating accurate phonon frequencies and eigenvectors for noble metal surfaces. The U.S.side will contribute in turn its expertise in calculating the linewidths of surface phonons, which stems from their comprehensive program studying anharmonic effects at crystal surfaces.