Fully Anharmonic Thermoelectric Efficiencies from First Principles

The computational design of improved materials with optimal thermoelectric efficiency zT requires to tailor both the electronic and the vibrational transport coefficients. With respect to the latter, ab initio molecular dynamics (aiMD) calculations have revealed that strongly anharmonic effects associated to short-lived distortions are highly beneficial for increasing zT. [1] However, an accurate first-principles assessment of electronic transport is challenging when such strongly anharmonic effects are active, since different electronic conduction mechanism can compete in this regime. In this work, we overcome this hurdle by combining approaches suited for assessing ionic conductivities, i.e., the Berry phase formalism, with temperature-dependent electronic-structure theory approaches [2] suited for assessing band-type transport in semiconductors. In turn, this allows to evaluate electronic fluxes along aiMD trajectories und to utilize the Green-Kubo formula to obtain accurate transport coefficients for arbitrarily anharmonic semi-conductors.



[1] F. Knoop, et al., arXiv:2209.12720 (2022).

[2] M. Zacharias, et al., Phys. Rev. B 102, 045126 (2020).