Strong anharmonic and quantum effects in Pm3¯n AlH3 under high pressure: A first-principles study
Motivated by the absence of experimental superconductivity in the metallic Pm¯3n phase of AlH3 despite the predictions, we reanalyze its vibrational and superconducting properties at pressures P≥99 GPa making use of first-principles techniques. In our calculations based on the self-consistent harmon...
| Autores: | , , , |
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| Tipo de recurso: | artículo |
| Estado: | Versión publicada |
| Fecha de publicación: | 2021 |
| País: | España |
| Institución: | Consejo Superior de Investigaciones Científicas (CSIC) |
| Repositorio: | DIGITAL.CSIC. Repositorio Institucional del CSIC |
| OAI Identifier: | oai:digital.csic.es:10261/258872 |
| Acceso en línea: | http://hdl.handle.net/10261/258872 |
| Access Level: | acceso abierto |
| Sumario: | Motivated by the absence of experimental superconductivity in the metallic Pm¯3n phase of AlH3 despite the predictions, we reanalyze its vibrational and superconducting properties at pressures P≥99 GPa making use of first-principles techniques. In our calculations based on the self-consistent harmonic approximation method that treats anharmonicity beyond perturbation theory, we predict a strong anharmonic correction to the phonon spectra and demonstrate that the superconducting critical temperatures predicted in previous calculations based on the harmonic approximation are strongly suppressed by anharmonicity. The electron-phonon coupling concentrates on the lowest-energy hydrogen-character optical modes at the X point of the Brillouin zone. As a consequence of the strong anharmonic enhancement of their frequency, the electron-phonon coupling is suppressed by at least 30%. The suppression in λ makes Tc smaller than 4.2 K above 120 GPa, which is well consistent with the experimental evidence. Our results underline that metal hydrides with hydrogen atoms in interstitial sites are subject to huge anharmonic effects. |
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