We study the gap closure with pressure of crystalline molecular hydrogen. The gaps are obtained from grand-canonical Quantum Monte Carlo methods properly extended to quantum and thermal crystals, simulated by Coupled Electron Ion Monte Carlo. Nuclear zero point effects cause a large reduction in the gap ($\sim 2eV$). the fundamental indirect gap closes 530GPa for ideal crystals and 330-380GPa for quantum crystals. Beyond this pressure the system enters into a bad metal phase where the density of states at the Fermi level increases with pressure up to $$450 GPa when the direct gap closes. Our work partially supports the interpretation of recent experiments in high pressure hydrogen.

中文翻译：

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压力下晶体分子氢的能隙闭合

我们研究了晶体分子氢的压力下的间隙闭合。这些间隙是从耦合电子离子蒙特卡洛模拟的大正则量子蒙特卡洛方法获得的，该方法适当地扩展到了量子和热晶体。核零点效应会导致间隙大幅减小（$〜2ËV$）。理想晶体的基本间接间隙为530GPa，量子晶体为330-380GPa。超过此压力，系统进入不良金属阶段，当直接间隙闭合时，费米能级下的态密度随着压力增加至$ 450 GPa而增加。我们的工作部分支持对高压氢最新实验的解释。