Electronic Structure of Condensed Matter

凝聚态物质的电子结构

• 批准号: 9802373
• 负责人: David Ceperley
• 金额: $ 52.5万
• 依托单位: University of Illinois at Urbana-Champaign
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 1998
• 资助国家: 美国
• 起止时间: 1998-08-01 至 2001-07-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=9802373&HistoricalAwards=false
• 关键词: Electronic; Structure; Condensed; Matter

9802373 Ceperley The long range goal of this research is to develop practical, efficient theoretical methods to accurately predict the properties of many-electron systems. Theoretical methods and computational algorithms are being generated that can be applied to important idealized systems, such as the homogeneous electron gas, as well as to realistic problems in atoms, molecules, and condensed matter. The approach taken is a combination of quantum Monte Carlo (QMC) simulations and density functional theory (DFT). QMC can provide exact results for some many-body problems and the range of problems for which this method can be applied is being extended. DFT is the only method feasible for large-scale simulations of real systems. Research objectives include the development of QMC methods with emphasis on the improvement of the nodal surfaces for fermion wavefunctions which is the limiting factor in the accuracy of the algorithms. A method has been developed to dynamically optimize the nodal surface and will be applied to many-electron systems. Work will also continue to calculate forces with QMC methods. First applications will be for forces between protons in an electron gas. Applications of QMC methods to physical problems will include nanoscale quantum devices and lower dimensional systems; electron-hole plasmas where finite-temperature techniques will be used to srudy the formation of excitons, bi-excitons, and the superconducting state; and hydrogen impurities in metals, which is a test of DFT and an important problem in materials science. New work on the phases of hydrogen at high pressure will focus on prediction of infrared activity using the Berry's phase formulation. Also to be developed will be general theoretical methods for studying dielectric polarization in correlated systems. The first test of the new ideas are being implemented in lattice models and methods will be developed for real systems. Many- body calculations will be used to test approximate DFT functionals and to derive new forms. Long term challenges are to develop algorithms to solve the famous "sign problem" which is a limiting factor in application of Monte Carlo methods to fermions and dynamics; to develop robust "order-N' linear scaling methods that go beyond approximate DFT methods; and to apply these methods to outstanding materials problems. %%% The long range goal of this research is to develop practical, efficient theoretical methods to accurately predict the properties of many-electron systems. Theoretical methods and computational algorithms are being generated that can be applied to important idealized systems, such as the homogeneous electron gas, as well as to realistic problems in atoms, molecules, and condensed matter. Long term challenges are to develop algorithms to solve the famous "sign problem" which is a limiting factor in application of Monte Carlo methods to fermions and dynamics; to develop robust "order-N' linear scaling methods that go beyond approximate DFT methods; and to apply these methods to outstanding materials problems. ***

9802373 Ceperley本研究的长期目标是开发实用，有效的理论方法，以准确地预测多电子系统的属性。 正在产生的理论方法和计算算法可以应用于重要的理想化系统，例如均匀电子气，以及原子、分子和凝聚态物质中的现实问题。 所采取的方法是量子蒙特卡罗（QMC）模拟和密度泛函理论（DFT）的组合。 QMC方法可以对某些多体问题提供精确的结果，其应用范围正在扩大。 DFT是对真实的系统进行大规模模拟的唯一可行的方法。 研究目标包括QMC方法的发展，重点是改进费米子波函数的节面，这是算法准确性的限制因素。 提出了一种动态优化节面的方法，并将应用于多电子系统。 还将继续使用QMC方法计算力。 第一个应用将是电子气中质子之间的力。 QMC方法在物理问题上的应用将包括纳米级量子器件和低维系统;电子-空穴等离子体，其中有限温度技术将用于研究激子、双激子和超导态的形成;金属中的氢杂质，这是对密度泛函理论的考验，也是材料科学中的一个重要问题。 新的工作阶段的氢在高压下将集中在预测红外活动使用贝里的相位公式。 还将发展研究相关系统中的介电极化的一般理论方法。 新思想的第一次测试正在格模型中实施，方法将为真实的系统开发。 多体计算将被用来测试近似的DFT泛函和导出新的形式。 长期的挑战是开发算法来解决著名的“符号问题”，这是一个限制因素，在应用蒙特卡罗方法费米子和动力学;开发强大的“N阶”线性标度方法，超越近似DFT方法;并将这些方法应用于突出的材料问题。 本研究的长期目标是开发实用，有效的理论方法，以准确地预测多电子系统的属性。 正在产生的理论方法和计算算法可以应用于重要的理想化系统，例如均匀电子气，以及原子、分子和凝聚态物质中的现实问题。 长期的挑战是开发算法来解决著名的“符号问题”，这是一个限制因素，在应用蒙特卡罗方法费米子和动力学;开发强大的“N阶”线性标度方法，超越近似DFT方法;并将这些方法应用于突出的材料问题。 ***