Path Integral Monte Carlo Simulations of Dense Plasma

在先进核反应堆和惯性约束聚变、冲击物理、等离子体科学和储存管理等关键能源技术的发展中，了解材料在热致密物质(WDM)和高密度等离子体区域中的理论性质是一个中心目标。该项目首次开发了一种创新的新技术来模拟第二排材料元素的致密等离子体。该项目将使用Blue Waters领导系统将这一新技术应用于一些关键材料，以便为冲击波实验提供指导，并为其他理论方法建立基准。该项目建议在温度-密度点网格上模拟一组材料，以推导出等离子体条件下和波分复用条件下的状态方程(EOS)。该项目的结果将对国家点火设施(NIF)和其他高能量密度物理设施的设计者具有不可估量的重要性。学生们将广泛参与这个项目，该项目将推进美国国家科学基金会的任务，以支持可能对国家做出贡献的基础研究-S繁荣。为了研究波分复用制度，该项目将结合新的PIMC模拟和标准的Kohn-Sham密度泛函分子动力学(KS-DFMD)模拟，后者在较低温度下更有效。虽然KS-DFMD已经被用来准确地预测温度高达100000 K的许多固体和液体的结构，但它不适用于更高的温度，因为部分占据的电子轨道数达到了难以处理的大数字。另一种方法是轨道自由密度泛函分子动力学(OF-DFMD)，由于还没有发展出现有的自由能泛函，所以得到的EOS结果不准确。能源部(DOE)国家实验室的合作者将使用PIMC状态方程数据与现有的半经验状态方程生成方案进行比较，并作为连续辐射流体力学模拟的输入。该项目旨在建立一条从PIMC到材料响应的宏观连续统研究的有效渠道。重点将放在对在极高温度(~100 eV)和低密度下产生的重元素等离子体的这种方法进行基准测试，这些等离子体是在间接驱动激光实验中霍耳辐射加热烧蚀材料时产生的。

Understanding the theoretical properties of materials in the warm dense matter (WDM) and dense plasma regimes is a central goal in the development of key energy technologies, such as advanced nuclear reactors and inertial confined fusion, shock physics, plasma science, and stockpile stewardship. The project has developed an innovative new technique to simulate dense plasmas of second-row material elements for the first time. The project will use the Blue Waters leadership system to apply this new technique to a number of key materials in order to provide guidance to shock wave experiments and establish benchmarks for other theoretical approaches. The project proposes to simulate a set of materials on a grid of temperature-density points in order to derive the equation of state (EOS) under plasma conditions and in the regime of WDM. Results from this project will be of immeasurable importance to the designers at the National Ignition Facility (NIF) and at other high-energy-density-physics facilities. Students will be extensively involved with the project, which advances the NSF mission to support basic research that may contribute to the nation?s prosperity.To study the WDM regime, the project will combine a novel PIMC simulations with standard, Kohn-Sham density functional molecular dynamics (KS-DFMD) simulations, which are more efficient at lower temperatures. While KS-DFMD has been used to accurately predict the structure of many solids and liquids up to temperatures on the order of 100,000 K, it is not applicable at much higher temperaturesbecause the number of partially occupied electronic orbitals reaches intractably large numbers. The alternate method, orbital-free density functional molecular dynamics (OF-DFMD) yields inaccurate EOS results because no existing free energy functional has been developed. Collaborators at Department of Energy (DOE) national labs will use the PIMC EOS data both as comparisons to existing semi-empirical, EOS-generating schemes, and as inputs for continuum radiation hydrodynamics simulations. The project aims to establish an efficient pipeline from PIMC to macroscopic continuum studies of materials response. An emphasis will be placed on benchmarking such methods for plasmas of heavy elements at very high temperatures (~100 eV) and low densities that are generated when Hohlraum radiation heats the ablator material in indirect drive laser experiments.