elphbolt: An ab initio solver for the coupled and decoupled electron and phonon Boltzmann transport equations*

Calculation of the electron-phonon (e-ph) drag effect requires addressing the self-consistent transport of both these species. Here we present elphbolt [1] -- a free/libre software for solving both the coupled and decoupled e and ph Boltzmann transport equations. This software allows the efficient calculation of the effect of the mutual e-ph drag on the thermal and charge conductivities, and the thermopower. The code uses ab initio e-ph and ph-ph couplings and employs a novel iterative procedure that enforces the Kelvin-Onsager relationship between the Seebeck and the Peltier thermopowers, as mandated by thermodynamics. The code also takes advantage of the coarray feature of modern Fortran, which provides convenient native syntax for parallelization. In this talk, we highlight the design and capabilities of the code with examples. The code is hosted at https://github.com/nakib/elphbolt.

[1] Protik, N. H., Li, C., Pruneda, M., Broido, D. and Ordejón, P., 2021. elphbolt: An ab initio solver for the coupled electron-phonon Boltzmann transport equations. arXiv preprint arXiv:2109.08547.