Cui Ting-Ting, Li Jian-Chen, Gao Wang, Hermann Jan, Tkatchenko Alexandre, Jiang Qing
Key Laboratory of Automobile Materials (Jilin University), Ministry of Education, Department of Materials Science and Engineering , Jilin University , Changchun 130022 , China.
Physics and Materials Science Research Unit , University of Luxembourg , L-1511 Luxembourg City , Luxembourg.
J Phys Chem Lett. 2020 Feb 20;11(4):1521-1527. doi: 10.1021/acs.jpclett.9b03716. Epub 2020 Feb 10.
High-pressure hydrogen exhibits remarkable phenomena including the insulator-to-metal (IM) transition; however, a complete resolution of its phase diagram is still an elusive goal despite many efforts and much controversy. Theoretical modeling is typically based on density functional theory (DFT) with a mean-field description of electronic correlations, which is known to be rather limited in describing IM transitions. Herein, we show that nonlocal electron correlations play a central role in the relative stability of solid hydrogen phases, and that DFT-correcting for these correlations by the many-body dispersion (MBD) model reaches the accuracy of quantum Monte Carlo (QMC) simulations and predicts the same 2/-24 → -12 → Cs(IV) IM transition. In contrast with the conventional assumption that many-body electronic correlations become localized in metallic systems because of exponential screening with interelectronic distance, we find that the anisotropy of the electronic response of hydrogen solids under pressure leads to longer-ranged many-body effects in metallic phases relative to insulating ones. This refines our understanding of phase diagram of hydrogen solids as well as anisotropic many-body correlations.
高压氢表现出包括绝缘体到金属（IM）转变在内的显著现象；然而，尽管付出了诸多努力且存在诸多争议，但要完整解析其相图仍是一个难以实现的目标。理论建模通常基于密度泛函理论（DFT），对电子关联采用平均场描述，而众所周知，这在描述IM转变方面相当有限。在此，我们表明非局域电子关联在固态氢相的相对稳定性中起核心作用，并且通过多体色散（MBD）模型对这些关联进行DFT校正可达到量子蒙特卡罗（QMC）模拟的精度，并预测相同的2/-24 → -12 → Cs(IV) IM转变。与传统假设不同，即由于电子间距离的指数屏蔽，多体电子关联在金属系统中会局域化，我们发现高压下氢固体电子响应的各向异性导致金属相相对于绝缘相具有更长程的多体效应。这深化了我们对氢固体相图以及各向异性多体关联的理解。
