Computing electron and phonon transport including drag: current state-of-the-art and what comes next

Capturing the transport phenomena in an interacting system of electrons and phonons requires one to self-consistently solve a coupled set of kinetic equations that govern how both types of particles go out of equilibrium. This formalism allows for the fact that the two types of particles exchange energy and momentum between them and, in the process, drag each other. It is now an established fact that the electronic and phononic transport phenomena are, in general, dragful as opposed to dragless. In recent times, dragful transport has become the new state-of-the-art in the field. Indeed, it has been shown that dragless transport often gives orders of magnitude wrong prediction for the thermopower. The charge mobility and phonon thermal conductivity, too, can be significantly underestimated in the dragless theories. This new state-of-the-art has been enabled by the Free/Libre/Open Source code elphbolt. In this talk, I will first guide the audience through the dragful electron-phonon transport theory as implemented in the elphbolt code and then highlight a selection of new features that we have developed since the last public release of the code.