Proton Quantum Effects in H${}_3$S Electronic Structure: A Multicomponent DFT study via Nuclear-Electronic Orbital Method

Abstract

We investigate the impact of the quantum effects of protons on the electronic structure of high-pressure H${}_3$S, a benchmark hydrogen-rich superconductor with a critical temperature ($T_c$) exceeding 200 K. Using Nuclear-Electronic Orbital Density Functional Theory (NEO-DFT), we treat hydrogen nuclei quantum mechanically on the same footing as electrons within a first-principles framework. Our calculations reveal that nuclear quantum effects (NQEs) induce subtle modifications to the electronic band structure and density of states (DOS) near the Fermi energy, including features associated with van Hove singularities. However, the resulting changes in the DOS would increase $T_c$ by only a few percent. On the other hand, calculations of the phonon dispersion with the NEO-DFT method show large changes in the hydrogen-dominated phonons that arise from a stiffening of the S-H bonds due to NQEs. These findings imply that the experimentally observed reduction in $T_c$ upon deuteration arises predominantly from changes in the phonon properties, while NQEs-induced modifications to the electronic structure itself are minimal.

9 pages, 5 figures

References in corpus (22)

• Conventional superconductivity at 203 K at high pressures
• Electron-phonon interactions from first principles
• Implementation strategies in phonopy and phono3py
• A Perspective on Conventional High-Temperature Superconductors at High Pressure: Methods and Materials
• Hydrogen sulphide at high pressure: a strongly-anharmonic phonon-mediated superconductor
• Quantum Hydrogen-Bond Symmetrization and High-Temperature Superconductivity in Hydrogen Sulfide
• First-Principles Theory of Anharmonicity and the Inverse Isotope Effect in Superconducting Palladium-Hydride Compounds
• What superconducts in sulfur hydrides under pressure, and why
• Cubic H${}_3$S around 200 GPa: an atomic hydrogen superconductor stabilized by sulfur
• First-principles study of the pressure and crystal-structure dependences of the superconducting transition temperature in compressed sulfur hydrides
• High-Temperature Superconductivity in Alkaline and Rare Earth Polyhydrides at High Pressure: A Theoretical Perspective
• Effect of van Hove singularities on high-Tc superconductivity in H3S
• Development of a Practical Multicomponent Density Functional for Electron-Proton Correlation to Produce Accurate Proton Densities
• van Hove singularities and spectral smearing in high temperature superconducting H3S
• Theory of the special displacement method for electronic structure calculations at finite temperature
• Breakdown of the Migdal approximation at Lifshitz transitions with giant zero-point motion in H3S superconductor
• Anharmonic lattice dynamics via the special displacement method
• Band structure and electron-phonon coupling in H${}_3$S:a tight-binding model
• Ab initio simulations of hydrogen-bonded ferroelectrics: collective tunneling and the origin of geometrical isotope effects
• Significance of nuclear quantum effects in hydrogen bonded molecular chains
• Nuclear-Electronic Orbital Approach to Quantization of Protons in Periodic Electronic Structure Calculations
• Electron-phonon vertex correction effect in superconducting H3S