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

被引:32
作者
Borinaga, Miguel [1 ,2 ]
Riego, P. [3 ,4 ]
Leonardo, A. [2 ,5 ]
Calandra, Matteo [6 ]
Mauri, Francesco [7 ]
Bergara, Aitor [1 ,2 ,4 ]
Errea, Ion [2 ,8 ]
机构
[1] CSIC UPV EHU, CFM, Paseo Manuel de Lardizabal 5, Donostia San Sebastian 20018, Basque Country, Spain
[2] DIPC, Manuel Lardizabal Pasealekua 4, Donostia San Sebastian 20018, Basque Country, Spain
[3] CIC NanoGUNE, Tolosa Hiribidea 76, Donostia San Sebastian 20018, Basque Country, Spain
[4] Univ Basque Country UPV EHU, Dept Fis Mat Condensada, Bilbao 48080, Basque Country, Spain
[5] Univ Basque Country UPV EHU, Zientzia & Teknol Fak, Fisika Aplikatua Saila 2, Bilbao 48080, Basque Country, Spain
[6] Univ Paris 06, Sorbonne Univ, UMR CNRS 7590, IMPMC,MNHN,IRD, 4 Pl Jussieu, F-75005 Paris, France
[7] Univ Roma La Sapienza, Dipartimento Fis, Piazzale Aldo Moro 5, I-00185 Rome, Italy
[8] Univ Basque Country UPV EHU, Bilboko Ingn Eskola, Fisika Aplikatua Saila 1, Rafael Moreno Pitxitxi Pasealekua 3, Bilbao 48013, Basque Country, Spain
关键词
molecular hydrogen; superconductivity; anharmonicity; SOLID HYDROGEN; DENSE HYDROGEN; PHASE; GPA; SYSTEM;
D O I
10.1088/0953-8984/28/49/494001
中图分类号
O469 [凝聚态物理学];
学科分类号
070205 ;
摘要
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.
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页数:7
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