近日，意大利罗马大学Francesco Mauri课题组与法国索邦大学的Michele Casula等人合作，提出了高压氢的量子相图。相关研究成果已于2023年3月13日在国际学术期刊《自然—物理学》上发表。
该团队使用最先进的方法描述了多体电子相关性和质子量子非谐运动，计算出了低温高压下氢和氘的相图。研究结果表明，长期寻找的原子金属氢相预计将在577(4)GPa具有室温超导性质。原子核的非谐振动将这个相的稳定性推向比以前估计或实验得到的压力更大的范围。在原子化之前，分子氢在410(20)GPa时从金属相(相III)转变为另一种仍然是分子的金属结构(相VI)。同位素效应使两种转变的压力分别增加了63和32GPa。研究人员预测了光谱学和直流电导率的特征，可用于实验中区分这两种结构转变。
据悉，氢是宇宙中最丰富的元素。然而，由于在兆巴级压力下，电子和质子的量子性质会显现出来，产生偏离凝聚态系统常见行为的现象，因此理解致密氢的性质仍然是一个挑战。实验很具有挑战性，只能获得有限的观测数据，并且电子相关性和核量子运动之间的相互作用使得标准模拟变得不可靠。
附：英文原文
Title: Quantum phase diagram of high-pressure hydrogen
Author: Monacelli, Lorenzo, Casula, Michele, Nakano, Kousuke, Sorella, Sandro, Mauri, Francesco
Issue&Volume: 2023-03-13
Abstract: Hydrogen is the most abundant element in the Universe. However, understanding the properties of dense hydrogen is still an open challenge because—under megabar pressures—the quantum nature of both electrons and protons emerges, producing deviations from the common behaviour of condensed-matter systems. Experiments are challenging and can access only limited observables, and the interplay between electron correlation and nuclear quantum motion makes standard simulations unreliable. Here we present the computed phase diagram of hydrogen and deuterium at low temperatures and high pressures using state-of-the-art methods to describe both many-body electronic correlation and quantum anharmonic motion of protons. Our results show that the long-sought atomic metallic hydrogen phase—predicted to host room-temperature superconductivity—forms at 577(4)GPa. The anharmonic vibrations of nuclei pushes the stability of this phase towards pressures much larger than previous estimates or attained experimental values. Before atomization, molecular hydrogen transforms from a metallic phase (phase III) to another metallic structure that is still molecular (phase VI) at 410(20)GPa. Isotope effects increase the pressures of both transitions by 63 and 32 GPa, respectively. We predict signatures in optical spectroscopy and d.c. conductivity that can be experimentally used to distinguish between the two structural transitions.
DOI: 10.1038/s41567-023-01960-5
Source: https://www.nature.com/articles/s41567-023-01960-5