Lorenzo Monacelli (Laboratoire de théorie et simulation des matériaux, Ecole Polytechnique Fédérale de Lausanne)
Titre : Quantum Fluctuations and Phonon Anharmonicity in High-Pressure Hybrides: Reshaping the Phase Diagram and Enhancing Superconductivity
Institut Néel, Salle E424 (Louis Weil)
Résumé : The role of phonon anharmonicity in determining the stability and vibrational properties of high-pressure hydrides and hydrogen is crucial. In fact, strong anharmonicity can challenge the standard approaches used to compute superconductivity and render the phonon quasiparticle picture obsolete. This seminar explores how quantum fluctuations reshape the high pressure phase diagram of hydrogen, LaH10, and H3S, shifting the phase boundaries up to 100 GPa. We also examine superconductivity in metallic hydrogen, accounting for the full anharmonic lineshape of the phonon spectral function and mode mixing. Our analysis shows that phonon anharmonicity substantially enhances the superconductive critical temperature, making it a crucial factor to consider in the search for room-temperature superconductivity.
