Quantitative nonlinear time-dependent density functional theory (TDDFT) for large systems

大型系统的定量非线性瞬态密度泛函理论 (TDDFT)

基本信息

批准号：
1763176
负责人：
Daniel Neuhauser
金额：
$ 39万
依托单位：
University of California-Los Angeles
依托单位国家：
美国
项目类别：
Standard Grant
财政年份：
2018
资助国家：
美国
起止时间：
2018-06-01 至 2023-05-31
项目状态：
已结题

来源：
https://www.nsf.gov/awardsearch/showAward?AWD_ID=1763176&HistoricalAwards=false
关键词：
Quantitative nonlinear time dependent density

项目摘要

AbstractDaniel Neuhauser at the University of California, Los Angeles, is supported by an award from the Chemical Theory, Models and Computational Methods (CTMC) Program in the Chemistry Division to explore electron motion in nanomaterials in response to intense laser irradiation. This is an interesting and complex regime where new phenomena are emerging but it remains largely unexplored since accurate theoretical and computational methods for the description of excited states can only be applied to small systems. Dr. Neuhauser and coworkers are developing new methods which incorporate the necessary quantum mechanical effects at moderate computational costs. A novel computational framework is being developed that merges quantum chemistry, condensed matter physics and applied mathematics through a probabilistic approach to the problem. Specific efforts are being made to involve undergraduate and high school students, and the project emphasizes leadership opportunities for graduate students and postdocs.To obtain the fundamental physical characteristics of complex systems, a fully ab-initio quantum description is necessary. The most suitable approach is to employ real time Time-Dependent Density Functional Theory (TDDFT) with long-range exact exchange which approximates quasiparticle energies and includes attractive electron-hole interactions. The latter are necessary to account for excitonic effects and the redistribution of spectral weight in absorption cross sections. However, conventional implementations severely limit the maximum size of the system that can be treated using TDDFT with exact exchange. The project develops a stochastic TDDFT method which simulates the exchange interaction stochastically, i.e., summations over all occupied states are replaced by random sampling of the occupied Hilbert subspace, while the remaining parts of the description can be simulated traditionally. This makes it possible to treat systems with thousands of atoms and calculate the nonlinear response for systems that could not be handled previously. Description of the optical response of highly inhomogeneous systems, e.g., defect states, is being treated with a new Embedded Stochastic TDDFT, which combines stochastic and deterministic TDDFT for different regions of space. Mentoring of students ranging from high school to postdoctoral status is provided through this work, and the software developed is being made available to the wider community.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.

加利福尼亚大学洛杉矶分校的AbstractDaniel Neuhauser得到了化学理论，模型和计算方法（CTMC）在化学部门的一项奖项的支持，该计划响应强烈的激光辐照，以探索纳米材料中的电子运动。这是一个有趣且复杂的制度，新现象正在出现，但在很大程度上没有探索，因为对于激发态的描述的准确理论和计算方法只能应用于小型系统。 Neuhauser博士和同事正在开发新的方法，这些方法以中等的计算成本结合了必要的量子机械效应。正在开发一种新型的计算框架，该框架通过解决问题的概率方法来合并量子化学，凝结物理学和应用数学。为了使本科生和高中生参与进来，该项目强调了研究生和博士学位的领导机会。要获得复杂系统的基本身体特征，需要完全ab-Initio量子描述。最合适的方法是采用实时依赖性密度功能理论（TDDFT），并具有远程精确交换，从而近似于准粒子能量，并包括有吸引力的电子孔相互作用。后者对于吸收横截面中的兴奋子效应和光谱重量的重新分布是必要的。但是，常规实现严重限制了可以使用TDDFT和精确交换来处理的系统的最大大小。该项目开发了一种随机的TDDFT方法，该方法可以随机地模拟交换交互，即，对所有被占领状态的总结被占用的希尔伯特子空间的随机抽样所取代，而描述的其余部分则可以模拟传统上。这使得可以使用数千个原子处理系统，并计算以前无法处理的系统的非线性响应。高度不均匀系统（例如缺陷状态）的光学响应的描述正在使用新的嵌入式随机TDDFT进行处理，该嵌入式随机TDDFT结合了不同空间区域的随机和确定性TDDFT。通过这项工作提供了从高中到博士后状态的学生的指导，并且为更广泛的社区提供了开发的软件。该奖项反映了NSF的法定任务，并被认为是通过基金会的智力优点和更广泛影响的审查标准通过评估来获得支持的。