Driver K P, Soubiran F, Zhang Shuai, Militzer B
Department of Earth and Planetary Science, University of California, Berkeley, California 94720, USA.
J Chem Phys. 2015 Oct 28;143(16):164507. doi: 10.1063/1.4934348.
We perform all-electron path integral Monte Carlo (PIMC) and density functional theory molecular dynamics (DFT-MD) calculations to explore warm dense matter states of oxygen. Our simulations cover a wide density-temperature range of 1-100 g cm(-3) and 10(4)-10(9) K. By combining results from PIMC and DFT-MD, we are able to compute pressures and internal energies from first-principles at all temperatures and provide a coherent equation of state. We compare our first-principles calculations with analytic equations of state, which tend to agree for temperatures above 8 × 10(6) K. Pair-correlation functions and the electronic density of states reveal an evolving plasma structure and ionization process that is driven by temperature and density. As we increase the density at constant temperature, we find that the ionization fraction of the 1s state decreases while the other electronic states move towards the continuum. Finally, the computed shock Hugoniot curves show an increase in compression as the first and second shells are ionized.
我们进行全电子路径积分蒙特卡罗（PIMC）和密度泛函理论分子动力学（DFT-MD）计算，以探索氧的温稠密物质状态。我们的模拟涵盖了1 - 100 g/cm³和10⁴ - 10⁹ K的宽广密度 - 温度范围。通过结合PIMC和DFT-MD的结果，我们能够从第一性原理计算所有温度下的压力和内能，并提供一个连贯的状态方程。我们将我们的第一性原理计算结果与解析状态方程进行比较，对于温度高于8×10⁶ K的情况，两者倾向于一致。对关联函数和电子态密度揭示了由温度和密度驱动的不断演化的等离子体结构和电离过程。当我们在恒定温度下增加密度时，我们发现1s态的电离分数降低，而其他电子态向连续区移动。最后，计算得到的冲击雨贡纽曲线表明，随着第一和第二壳层的电离，压缩增加。
