论文标题
观察到的氢的金属化解释为带状结构效应
Observed Metallization of Hydrogen Interpreted as a Band Structure Effect
论文作者
论文摘要
最近对氢金属化的实验研究通过最高〜425 GPA的红外测量跟踪了直接带隙和vibron频率[P. Loubeyre等人，自然577，631（2020）]。在此压力之上，直接间隙的不连续下降到低于最小实验可访问能量（〜0.1 eV）。作者认为，该观察结果是由C2/C-24分子相之间的结构相变为另一个分子相（例如CMCA-12）引起的。在这里，通过从头开始计算压力依赖性的Vibron频率和直接带隙，我们发现实验数据与最高425 GPA的C2/C-24阶段一致，并建议这种一致性超出了该压力。具体而言，我们发现C2/C-24相的带结构的质量变化导致直接带隙的不连续下降，这可以解释观察到的无结构过渡的下降。这种替代方案自然解释了测量中缺少滞后的情况。
A recent experimental study of the metallization of hydrogen tracked the direct band gap and vibron frequency via infrared measurements up to ~425 GPa [P. Loubeyre et al., Nature 577, 631 (2020)]. Above this pressure, the direct gap has a discontinuous drop to below the minimum experimentally accessible energy (~0.1 eV). The authors suggested that this observation is caused by a structural phase transition between the C2/c-24 molecular phase to another molecular phase such as Cmca-12. Here, through ab initio calculations of pressure dependent vibron frequency and direct band gap, we find that the experimental data is consistent with the C2/c-24 phase up to 425 GPa, and suggest that this consistency extends beyond that pressure. Specifically, we find that qualitative changes in the band structure of the C2/c-24 phase lead to a discontinuous drop of the direct band gap, which can explain the observed drop without a structural transition. This alternative scenario naturally explains the absence of hysteresis in the measurements.
