Electron-Phonon Interactions in Condensed Phases under Compression

Electron-phonon interactions in condensed phases are central to all important temperature-dependent properties of materials such as electrical resistance in metals, carrier mobility in semiconductors, and phase transitions in conventional superconductors. Based on all-electron quantum solid-state chemistry using density functional theory, non-perturbative calculations of electron-phonon interactions have been recently developed in condensed phases under compression. Such calculations can provide a clear understanding on the thermal dependence of electron energy bands and thermomechanically induced distortion of band structures to raise or lower the Fermi level, leading to the generation of charge and spin density waves mainly determined by amplitudes of vibrational motion under mechanical compression. More importantly, calculations also show how vibrational mode energies in the measure by vibrational amplitudes distribute to reach an equilibrium state and even to create a superconducting state with the temperature-dependent energy gap. High-pressure superconductors H₃S and LaH₁₀ are taken as examples to show calculation results in comparison with experiments.