Electronic Structure of Condensed Matter

本研究计划的长远目标是发展实用、有效的理论方法，以准确预测多电子系统的性质。由此产生的方法和计算算法可以应用于重要的理想系统，如均相电子气体，以及凝聚态物质中的现实问题。这些计算量子方法的快速发展将对包括物理学、材料科学、化学甚至生物学在内的许多科学领域的课程产生质的影响。该方法是量子蒙特卡罗模拟和密度泛函理论的结合。QMC可以为一些多体问题提供精确的结果，其主要目的是扩大该方法的应用范围。另一方面，DFT是目前唯一可行的对真实系统进行精确大规模模拟的方法。本研究既涉及基本理论，也涉及使用QMC的近似形式的检验。将继续发展QMC方法，重点是更精确的波函数和改进的边界条件，以及开发能够使用更大计算设施的新方法。QMC方法在物理问题上的应用将包括纳米级量子器件和无序存在的二维电子系统，其中关于可能的金属-绝缘体转变存在许多实验和理论争议。将发展研究相关体系中介电极化和泛函的一般理论方法。我们将把晶格模型的计算扩展到连续统系统，它可以作为改进通用密度偏振泛函的基础。我们还将继续最近开始的工作，使用时间相关的DFT来预测材料，纳米结构和量子点的激发光谱。研究的第一个系统将是硅团簇，在那里最近发现了强烈的蓝光发射。一个长期的目标是发展多体方法和改进的泛函，可以超越DFT近似的基态能量和激发光谱。本研究计划的长远目标是发展实用、有效的理论方法，以准确预测多电子系统的性质。由此产生的方法和计算算法可以应用于重要的理想系统，如均相电子气体，以及凝聚态物质中的现实问题。这些计算量子方法的快速发展将对包括物理学、材料科学、化学甚至生物学在内的许多科学领域的课程产生质的影响

0104399CeperleyThe long range goal of this research program is to develop practical, efficient theoretical methods to accurately predict the properties of many-electron systems. The methods and computational algorithms so generated can be applied to important idealized systems, such as the homogeneous electron gas, as well as to realistic problems in condensed matter. The rapid development of these computational quantum methods will have a qualitative impact upon the course of many fields of science including physics, materials science, chemistry and even biology.The approach is a combination of quantum Monte Carlo (QMC) simulations and density functional theory (DFT). QMC can provide exact results for some many-body problems, the principle goal is to extend the range of problems for which the method can be applied. On the other hand, DFT is the only current method feasible for accurate large-scale simulations of real systems. The research concerns both the basic theory, as well as tests of approximate forms using QMC. Continued development of QMC methods, with emphasis upon more accurate wavefunctions and improved boundary conditions and upon developing new methods able to use much larger computational facilities will be undertaken. Applications of QMC methods to physical problems will include nanoscale quantum devices and two-dimensional electron systems in the presence of disorder, where there is much experimental and theoretical controversy concerning the possible metal-insulator transition. General theoretical methods for studying dielectric polarization and functionals in correlated systems will be developed. We will extend the lattice model calculations to continuum systems that can serve as the basis for improved universal density-polarization functionals. We will also continue work started recently using time-dependent DFT to predict excitation spectra of materials, nanostructures and quantum dots. The first system studied will be silicon clusters, where intense blue light emission has been recently discovered. A long range goal is to develop both many-body methods and imporved functionals that can go beyond DFT approximations for ground state energies and excitation spectra.%%%The long range goal of this research program is to develop practical, efficient theoretical methods to accurately predict the properties of many-electron systems. The methods and computational algorithms so generated can be applied to important idealized systems, such as the homogeneous electron gas, as well as to realistic problems in condensed matter. The rapid development of these computational quantum methods will have a qualitative impact upon the course of many fields of science including physics, materials science, chemistry and even biology.***