First principles investigation of the structural, electronic, thermal and transport properties of new ternary auride $$\hbox {X}_{3}$$AuO (X = K and Rb) semiconductors

Abstract

We report the structural, electronic, thermal and transport properties of two new ternary aurides containing gold atom \(\hbox {X}_{3}\)AuO (X = K and Rb) using the full-potential linearized augmented plane wave method, based on the density functional theory. To describe the exchange-correlation potential, we have employed the generalized gradient approximation–Perdew–Burke–Ernzerhof (GGA–PBE) scheme of the GGA. The computed ground state properties are in good accordance with the experiments. Moreover, Tran–Blaha-modified Becke–Johnson (TB–mBJ) potential improves the electronic properties and gives accurate band gaps. Both anti-perovskites \(\hbox {X}_{3}\)AuO are semiconductors with an indirect band gap. Furthermore, the inclusion of spin–orbit coupling effects on the band structure along with TB–mBJ approximation splits the valence band of our compounds and reduces their band gap energy. The thermodynamic properties including heat capacity (\(C_{\mathrm{V}})\), thermal expansion (\(\alpha \)) and Debye temperature (\(\Theta _{\mathrm{D}})\) are also estimated. The transport properties as function of temperature are calculated using the BoltzTrap code; therefore, these two materials are very appropriate for thermoelectric devices at high temperatures.