npj: 研究固态氢相的前提—电子结构理论方法
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氢是宇宙中最轻和最丰富的元素,但在高压和低温下其相图仍然难以厘清。由于核和电子相关量子效应之间的微妙相互作用,关于在高压下哪种物质状态稳定的问题长期悬而未决。高压相的候选对象可能包括各种取向有序的分子晶体、(液态)金属、超导和超流体体系。这些潜在的外来物质状态及其对天体物理学、行星科学和材料科学的至关重要性,已招致理论、实验和技术上的深入研究。然而,相对于所采用的方法,当前计算和测量得到的平衡相界结果变化很大,且部分误差源难以控制,影响较大。
A comparative study using state-of-the-art electronic structure theories on solid hydrogen phases under high pressures
Ke Liao, Xin-Zheng Li, Ali Alavi & Andreas Grüneis
Determining the Wigner–Huntington transition using theoretical methods is extremely challenging. Despite the significant advancements of modern ab initio theories in the past decades, the preidentifying the atomic structure and properties of solid hydrogen under high pressures is a long-standing problem of high-pressure physics with far-reaching significance in planetary and materials science. Determining the pressure-temperature phase diagram of hydrogen is challenging for experiment and theory due to the extreme conditions and the required accuracy in the quantum mechanical treatment of the constituent electrons and nuclei, respectively. Here, we demonstrate explicitly that coupled cluster theory can serve as a computationally efficient theoretical tool to predict solid hydrogen phases with high accuracy.We present a first principles study of solid hydrogen phases at pressures ranging from 100 to 450 GPa. The computed static lattice enthalpies are compared to state-of-the-art diffusion Monte Carlo results and density functional theory calculations.Our coupled cluster theory results for the most stable phases including C2/c-24 and P211/c-24 are in good agreement with those obtained using diffusion Monte Carlo, with the exception of Cmca-4, which is predicted to be significantly less stable.We discuss the scope of the employed methods and how they can contribute as efficient and complementary theoretical tools to solve the long-standing puzzle of understanding solid hydrogen phases at high pressures.
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