Center for Advanced Systems Understanding (CASUS), D-02826 Görlitz, Germany.
Helmholtz-Zentrum Dresden-Rossendorf (HZDR), Institute of Radiation Physics, D-01328 Dresden, Germany.
Phys Rev E. 2023 Jan;107(1-2):015206. doi: 10.1103/PhysRevE.107.015206.
We combine ab initio path integral Monte Carlo (PIMC) simulations with fixed ion configurations from density functional theory molecular dynamics (DFT-MD) simulations to solve the electronic problem for hydrogen under warm dense matter conditions [Böhme et al., Phys. Rev. Lett. 129, 066402 (2022)0031-900710.1103/PhysRevLett.129.066402]. The problem of path collapse due to the Coulomb attraction is avoided by utilizing the pair approximation, which is compared against the simpler Kelbg pair potential. We find very favorable convergence behavior towards the former. Since we do not impose any nodal restrictions, our PIMC simulations are afflicted with the notorious fermion sign problem, which we analyze in detail. While computationally demanding, our results constitute an exact benchmark for other methods and approximations within DFT. Our setup gives us the unique capability to study important properties of warm dense hydrogen such as the electronic static density response and exchange-correlation kernel without any model assumptions, which will be very valuable for a variety of applications such as the interpretation of experiments and the development of new XC functionals.
我们将从头算路径积分蒙特卡罗（PIMC）模拟与密度泛函理论分子动力学（DFT-MD）模拟中的固定离子构型相结合，以解决温稠密物质条件下的氢的电子问题[Böhme 等人，Phys. Rev. Lett. 129, 066402 (2022)0031-900710.1103/PhysRevLett.129.066402]。通过利用对易近似避免了由于库仑吸引而导致的路径坍塌问题，我们将其与更简单的 Kelbg 对势进行了比较。我们发现前者的收敛行为非常有利。由于我们没有施加任何节点限制，我们的 PIMC 模拟受到了臭名昭著的费米子符号问题的困扰，我们对此进行了详细分析。虽然计算要求很高，但我们的结果构成了 DFT 内其他方法和近似的精确基准。我们的设置使我们能够在不进行任何模型假设的情况下研究温稠密氢的重要性质，例如电子静态密度响应和交换相关核，这对于各种应用非常有价值，例如实验解释和新 XC 泛函的开发。
