We use path integral Monte Carlo and density functional molecular dynamics to construct a coherent set of equation of state for a series of hydrocarbon materials with various C:H ratios (2:1, 1:1, 2:3, 1:2, and 1:4) over the range of $0.07-22.4$ g/cm$^{3}$ and $6.7\times10^3-1.29\times10^8$ K. The shock Hugoniot curve derived for each material displays a single compression maximum corresponding to $K$-shell ionization. For C:H=1:1, the compression maximum occurs at 4.7-fold of the initial density and we show radiation effects significantly increase the shock compression ratio above 2 Gbar, surpassing relativistic effects. The single-peaked structure of the Hugoniot curves contrasts with previous work on higher-$Z$ plasmas, which exhibit a two-peak structure corresponding to both $K$- and $L$-shell ionization. Analysis of the electronic density of states reveals that the change in Hugoniot structure is due to merging of the $L$-shell eigenstates in carbon, while they remain distinct for higher-$Z$ elements. Finally, we show that the isobaric-isothermal linear mixing rule for carbon and hydrogen EOSs is a reasonable approximation with errors better than 1% for stellar-core conditions.
First-Principles Simulations of Warm Dense Lithium Fluoride
我们进行第一性原理路径积分蒙特卡罗（PIMC）和密度泛函理论分子动力学（DFT-MD）计算，以探索温暖的致密物质状态的LiF。我们的模拟覆盖了$2.08-15.70$ ~g、$\,$、cm、$^{-3}$和$10^4-10^9$ ~K的宽密度-温度范围。由于PIMC和DFT-MD精确地处理原子壳层结构的影响，我们发现一个明显的压缩最大值和一个肩膀上的主要Hugoniot曲线归因于K-壳层和L-壳层电离。结果为广泛使用的EOS表，如SEEOS，LEOS和模型提供了基准。此外，我们计算对关联函数，揭示了一个不断变化的等离子体结构和电离过程，驱动的热和压力电离。最后，我们计算电子态密度的液体LiF的DFT-MD模拟，并发现，电子间隙可以保持开放的密度和温度增加到至少15.7克$~$ cm $^{-3}$。
Ionization and temperature measurements in warm dense copper using x-ray absorption spectroscopy
Lawrence Livermore National Laboratory（劳伦斯利弗莫尔国家实验室）；Mechanical and Aerospace Engineering, University of California San Diego（加州大学圣地亚哥分校机械与航空航天工程系）；Laboratory for Laser Energetics, University of Rochester（罗切斯特大学激光能量学实验室）；Sandia National Laboratories（桑迪亚国家实验室）
Thermal and Pressure Ionization in Warm, Dense MgSiO$_3$ Studied with First-Principles Computer Simulations
利用路径积分蒙特卡罗和密度泛函分子动力学（DFT-MD）模拟方法，研究了MgSiO $_3$顽火辉石在暖稠密物质区的性质.我们产生了一个一致的状态方程（EOS），跨越了很宽的温度和密度范围（10 $^4$-10 $^7$ K和6.42- 64.16 g cm $^{-3}$）。导出了冲击Hugoniot曲线，与实验符合得很好。我们确定的边界之间的制度的热电离和压力电离的定位在恒定温度下的内能达到最小值作为密度或压力的函数。在低密度下，随着自由态重量的变化，内能随着密度的增加而减小。热电离占主导地位。相反地，在高密度下，在压力电离状态下，内能随密度增加。我们确定两个制度之间的边界，并表明，压缩最大值沿冲击Hugoniot曲线发生，因为K壳层电子成为热电离，而不是压力电离。
Equation of state and transport coefficients of warm dense aluminum from mixed deterministic-stochastic density functional theory
Institute of Applied Physics and Computational Mathematics（应用物理与计算数学研究所）；National Key Laboratory of Computational Physics（计算物理学国家重点实验室）；Tianfu Institute of Innovative Energy Research（天府创新能源研究院）
Microscopy X-ray Imaging enriched with Small Angle X-ray Scattering for few nanometer resolution reveals shock waves and compression in intense short pulse laser irradiation of solids
Technical University Dresden（德累斯顿工业大学）；SLAC National Accelerator Laboratory（斯坦福直线加速器中心）；Leibniz Institute of Photonic Technology（莱布尼茨光子技术研究所）
