Crystal structure and superconductivity in atomic hydrogen: Deformation between I41/amd and Fddd
Crystal structure and superconductivity in atomic hydrogen: Deformation between I41/amd and Fddd
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DOI：
10.1088/1742-6596/950/4/042009
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发表时间：
2017-10
期刊：
影响因子：
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通讯作者：
T. Ishikawa;H. Nagara;T. Oda;N. Suzuki;K. Shimizu
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文献类型：
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作者：
T. Ishikawa;H. Nagara;T. Oda;N. Suzuki;K. Shimizu
我们利用势能表面跋涉进行结构搜索，研究了固体金属氢的晶体结构。我们将该技术应用于压力为 500 和 600 GPa 的四方 I41/amd 结构，并获得了向多个斜方 Fddd 结构的转变，这些结构是由 I41/amd 的 ab 平面扭曲形成的。通过很少的跋涉步骤就可以轻松克服势垒，这表明固体金属氢晶体结构相对于变形而言是软化的，并且很容易在 I41/amd 和 Fddd 结构之间波动。计算得出的超导临界温度显示，在 500 GPa 下，I41/amd 为 269 K，Fddd 为 263 K。当加压至 600 GPa 时，结构会软化，电子-声子耦合会增强。结果，I41/amd 的超导临界温度提高到 281 K，而 Fddd 由于其声子软化程度比 I41/amd 更大，超导临界温度降低到 252 K。
We investigated crystal structures of solid metallic hydrogen using the potential energy surface trekking for structure search. We applied this technique to a tetragonal I41/amd structure at pressures of 500 and 600 GPa and obtained the transformation into multiple orthorhombic Fddd structures, which are formed by distortions in the ab plane of I41/amd. The potential barriers are easily surmounted by few trekking steps, which indicates that in solid metallic hydrogen crystal structure is softened with respect to the distortion and is easily fluctuated among the I41/amd and Fddd structures. Calculated superconducting critical temperatures show 269 K for I41/amd and 263 K for Fddd at 500 GPa. The structures are softened and the electron-phonon coupling are enhanced with pressurization to 600 GPa. As the results, the superconducting critical temperature is increased to 281 K for I41/amd, whereas it is decreased to 252 K for Fddd owing to its larger phonon softening than that of I41/amd.