Anharmonic enhancement of superconductivity in metallic molecular Cmca-4 hydrogen at high pressure: a first-principles study

作者：Borinaga Miguel; Riego P; Leonardo A; Calandra Matteo; Mauri Francesco; Bergara Aitor; Errea Ion

来源：Journal of Physics: Condensed Matter , 2016, 28(49): 494001.

DOI：10.1088/0953-8984/28/49/494001

• molecular hydrogen
• superconductivity
• anharmonicity

First-principles calculations based on density-functional theory including anharmonicity within the variational stochastic self-consistent harmonic approximation are applied to understand how the quantum character of the proton affects the candidate metallic molecular Cmca - 4 structure of hydrogen in the 400-450 GPa pressure range, where metallization of hydrogen is expected to occur. Anharmonic effects, which become crucial due to the zero-point motion, have a large impact on the hydrogen molecules by increasing the intramolecular distance by approximately a 6%. This induces two new electron pockets at the Fermi surface opening new scattering channels for the electron-phonon interaction. Consequently, the electron-phonon coupling constant and the superconducting critical temperature are approximately doubled by anharmonicity and Cmca - 4 hydrogen becomes a superconductor above 200 K in all the studied pressure range. Contrary to many superconducting hydrides, where anharmoncity tends to lower the superconducting critical temperature, our results show that it can enhance superconductivity in molecular hydrogen.

• 出版日期2016-12-14