We find that 20 out of the 44 Zintl phases have estimated maximum zT (at 300 K) more than 20% of Mg 3 Bi 2 . Subsequently, we calculate the electronic structures of the 20 phases with a higher accuracy hybrid DFT functional (HSE06), including relativistic spin-orbit coupling (SOC) e↵ects. In addition to the 20 phases, we also calculate the electronic structures of 9 randomly chosen Zintl phases out of the remaining 24 phases. In total, we compute the electronic structures of 29/44 phases with hybrid DFT functional. The calculation details are elaborated in Section 5. The computed material descriptors for these 29 phases are reported in Table . The predicted TE performance as a function of R and band gap are plotted in Figure . Below, we discuss the material descriptors and predicted TE performance of Mg 3 Bi 2 (Figure ) and the top four candidate Zintl phases (Figures ).