A multiscale computational approach to the thermoelectric of β-Cu2Se: Combining DFT+U and molecular dynamics

Thermoelectric materials offer a direct pathway for mitigating the global energy crisis by converting waste heat into usable electricity; however, their efficiency must be improved for largescale applications. To this end, we evaluate the high-potential material β -Cu 2 Se through an integrated multiscale computational approach combining first-principles DFT+ U calculations and molecular dynamics (MD) simulations. Our results reveal that β -Cu 2 Se exhibits semiconducting behavior with a direct band gap of approximately 1.3 eV. The lattice thermal conductivity, κ l , calculated via non-equilibrium molecular dynamics, decreases from 0.905 Wm −1 K −1 at 300 K to 0.410 Wm −1 K −1 at 800 K due to the superionic transition and enhanced phonon scattering. Over the temperature range of 300–800 K, the thermoelectric figure of merit, ZT , increases from 0.184 to 0.747, with peak performance at elevated temperatures driven by a high Seebeck coefficient and suppressed thermal conductivity. This study provides the first integrated DFT+ U and MD assessment of both electronic and lattice thermal transport in β -Cu 2 Se, offering a comprehensive evaluation of ZT that bridges the gap between electronic structure calculations and lattice dynamics simulations. Our findings demonstrate that β -Cu 2 Se possesses favorable thermoelectric performance, making it a strong candidate for mid- to high-temperature energy conversion applications.