Ab-initio Quantum Monte Carlo Simulations of Warm Dense Matter

这个项目的重点是热稠密物质（WDM）的热力学和输运性质-固体和等离子体之间的边界上的一个外来状态。WDM对于理解天体物理对象（巨行星，矮星等）具有根本的重要性。以及在极压或高激发下的物质。近年来，这种状态可以在自由电子激光设备中进行实验研究，新的诊断方法可以进行精确的分析。这对理论和模拟都提出了挑战。然而，WDM的复杂性质-强相关性，电子量子效应，部分电离和有限的温度-只允许定性描述。密度泛函理论（DFT）的使用已经在这一领域取得了重大进展，但DFT需要有关有限温度下电子的交换相关自由能fXC的信息。 在这个项目的第一阶段，我们可以解决这个问题。我们开发了一种新的路径积分蒙特卡罗（PIMC）模拟方法-排列阻塞PIMC（PB-PIMC），它使我们能够准确地计算电子的热力学性质。本建议旨在继续这些发展。我们计划将模拟扩展到巨正则系综和其他观测量的计算，包括输运性质，松原绿色函数和光谱函数。最后，我们计划在WDM条件下将模拟扩展到氢。预期的高精度结果将使我们能够验证早期模型和模拟的数据，并最终提出改进这些方法的建议。此外，我们将能够为实验做出准确的预测。

This project focuses on the thermodynamic and transport properties of warm dense matter (WDM) – an exotic state on the boarder between solid and plasma. WDM is of fundamental importance for understanding astrophysical objects (giant planets, dwarf stars etc.) as well as for matter under extreme pressure or high excitation. In recent years such states became accessible for experimental investigation in free electron laser facilities, and new diagnostics enabled precise analysis. This poses a challenge to theory and simulation. However, the complex properties of WDM – strong correlations, electronic quantum effects, partial ionization and finite temperatures – allow only for a qualitative description. The use of density functional theory (DFT) has allowed for significant progress in this field, but DFT requires information about the exchange correlation free energy, fXC , of the electrons at finite temperature. In the first phase of this project we could solve this problem. We developed a new path integral Monte Carlo (PIMC) simulation method – permutation blocking PIMC (PB-PIMC) – which allowed us to compute the thermodynamic properties of the electrons exactly. The present proposal aims at continuation of these developments. We plan to extend the simulations to the grand canonical ensemble and to the computation of additional observables, including transport properties, the Matsubara Green function, and the spectral function. Finally, we plan to extend the simulations to hydrogen under WDM conditions. The expected high accuracy of the results will allow us to verify data from earlier models and simulations and, eventually suggest improvements of those approaches. Moreover, we will be able to make accurate predictions for experiments.