Abstract

The theoretical prediction of electrical and thermal transport properties of materials relies on an accurate description of electrons, phonons, and their interactions. While first-principles methods based on density functional theory can describe these material-specific quasiparticle properties and couplings, using this information to comprehensively calculate transport coefficients remains challenging. To address this, we developed Phoebe, a first-principles code which utilizes electron-phonon and phonon-phonon interactions to predict the transport properties of materials by solving the Boltzmann transport equation (BTE) using a full scattering matrix formalism.

Using this new framework, we are able to investigate a spectrum of phenomena ranging from the electrical, thermal, and thermoelectric properties of traditional materials to more exotic transport effects. For example, for both electron and phonons, we can calculate the Wigner formulation of transport or study hydrodynamic transport within the relaxons formalism. Additionally, we can study the impact of phonon-electron scattering on thermal conductivity, and through a pipeline with machine-learned force field calculations, can push the prediction of thermal conductivity to systems with hundreds of atoms. I will close by discussing possible directions for further predictions in transport as well as possible extensions to study other physical phenomena.