Theoretical Solid State Physics

该基金支持凝聚态物理和计算材料科学领域的长期、基础广泛的理论研究项目。研究项目涵盖半导体、金属、表面和界面、缺陷、超导、压力下材料、团簇、富勒烯基材料、纳米管和其他纳米结构、共轭聚合物、固体中的多电子效应等领域。主要目标是利用量子理论来解释和预测材料的性质。重点是使用现实的模型，与实验家密切合作，研究和建议生产新颖有用的材料，发展新的理论方法，并预测有关固体的电子和结构特性。在这个研究项目中，许多基于量子理论的新技术被开发出来，以实现对真实材料的精确计算。特别是，在密度泛函形式中应用从头算伪势方法和总能量技术来计算基态性质。用基于GW近似的第一性原理自能方法研究了准粒子激发的激发态（光谱）现象，用基于Bethe-Saltpeter方程的从头算两粒子格林函数方法研究了光激发的激发态（光谱）现象。其他研究依赖于变分和扩散蒙特卡罗方法、分子动力学模拟、介电函数方法、BCS理论、密度泛函微扰理论和标准多体理论的扩展。过去的成功包括对性能的准确预测和新材料的存在，允许带隙工程技术方法的电子结构计算，以及新的理论方法。这项研究计划以这项工作为基础，并向几个新的方向发展。具体项目包括理解和预测纳米管、富勒烯、分子结和其他纳米结构的性质；材料在环境和高压下的电子、振动和结构特性；固体材料的力学性能、弹性稳定性和极限强度；固体、缺陷和聚合物的电子-空穴相互作用和光学性质准粒子激发与电子关联；以及超导和新形式。在这项研究中有研究生和博士后的广泛参与。该基金支持凝聚态物理和计算材料科学领域的长期、基础广泛的理论研究项目。研究项目涵盖半导体、金属、表面和界面、缺陷、超导、压力下材料、团簇、富勒烯基材料、纳米管和其他纳米结构、共轭聚合物、固体中的多电子效应等领域。主要目标是利用量子理论来解释和预测材料的性质。重点是使用现实的模型，与实验家密切合作，研究和建议生产新颖有用的材料，发展新的理论方法，并预测有关固体的电子和结构特性。研究生和博士后广泛参与这项研究

This grant supports a long-range, broad-based theoretical research program in condensed matter physics and computational materials science. The research projects cover the fields of semiconductors, metals, surfaces and interfaces, defects, superconductivity, materials under pressure, clusters, fullerene-based materials, nanotubes and other nanostructures, conjugated polymers, and many-electron effects in solids. The major objective is to use quantum theory to explain and predict the properties of materials. Emphasis is placed on using realistic models, close collaboration with experimentalists, investigations and suggestions for producing novel and useful materials, development of new theoretical approaches, and predictions related to electronic and structural properties of solids.Many new techniques based on quantum theory were developed in this research program to enable accurate calculations of real materials. In particular, the ab initio pseudopotential method and total energy techniques are applied within the density functional formalism to compute ground-state properties. Excited-state (spectroscopic) phenomena are investigated using a first-principle self-energy approach based on the GW approximation for quasiparticle excitations and an ab initio two-particle Green's function method based on the Bethe-Saltpeter equation for optical excitations. Other studies rely on variational and diffusion Monte Carlo approaches, molecular dynamics simulations, dielectric function methods, BCS theory, density functional perturbation theory, and extensions of standard many-body theory.Past successes include accurate predictions of properties and the existence of new materials, electronic structure calculations which allow band-gap engineering approaches to technology, and new theoretical approaches. The research program builds on this work and goes in several new directions. Specific projects include those related to understanding and predicting the properties of nanotubes, fullerenes, molecular junctions, and other nanostructures; electronic, vibrational and structural properties of materials at ambient and high pressure; mechanical properties, elastic stability and limit of strength of solids; electron-hole interaction and optical properties of solids, defects and polymers; quasiparticle excitations and electron correlations; and superconductivity and new formalisms. There is extensive involvement of graduate students and postdoctoral associates in this research.%%%This grant supports a long-range, broad-based theoretical research program in condensed matter physics and computational materials science. The research projects cover the fields of semiconductors, metals, surfaces and interfaces, defects, superconductivity, materials under pressure, clusters, fullerene-based materials, nanotubes and other nanostructures, conjugated polymers, and many-electron effects in solids. The major objective is to use quantum theory to explain and predict the properties of materials. Emphasis is placed on using realistic models, close collaboration with experimentalists, investigations and suggestions for producing novel and useful materials, development of new theoretical approaches, and predictions related to electronic and structural properties of solids. There is extensive involvement of graduate students and postdoctoral associates in this research.***