Finite-Temperature Electronic Bands and Phonon Renormalization Modulate Thermoelectric Transport in ZrSnPt and ZrInAu

Abstract Finite-temperature thermoelectric calculations typically introduce temperature through carrier occupations and scattering rates while retaining zero-temperature electronic and vibrational states. Here, using ZrSnPt and ZrInAu as model systems, we retain first-principles-derived band- and k-resolved electronic energy shifts induced by thermal expansion and lattice vibrations and incorporate them directly into Boltzmann transport calculations. These nonuniform shifts modify band dispersion and valley alignment and lead to strongly material-, carrier-, and temperature-dependent transport responses. On the lattice side, we combine finite-temperature phonon renormalization and thermal expansion with three- and four-phonon scattering. The combined electronic and lattice effects produce relative changes in the thermoelectric figure of merit ZT ranging from −9.04% to +42.29% relative to the static reference treatment. These results highlight the importance of treating temperature-induced changes in transport-relevant electronic and vibrational states on a consistent footing for predictive thermoelectric transport calculations.