Effect of exchange-correlation functional type and spin-orbit coupling on thermoelectric properties of ZrTe2

Zirconium ditelluride is a layered two-dimensional transition-metal dichalcogenide and a topological Dirac semimetal. Due to the presence of heavy elements which lead to lower phonon frequencies and thus lower thermal conductivity, and have enhanced spin-orbit coupling, leading to topological properties, we investigate the potential of semi-metallic ZrTe2 for thermoelectric applications. Furthermore, given its anisotropic structure, the inplane and cross-plane transport properties are probed in order to understand which direction is favorable for better thermoelectric properties. In this work, we study the effect of different exchange-correlation (XC) functionals on the electronic band structure of ZrTe2. We show that band structure and specifically the bandgap is extremely sensitive to the choice of the XC functional and the inclusion of the spin-orbit interaction in the model. As a result, the electronic and thermoelectric properties are also significantly affected. As expected, the hybrid functional HSE thorn SOC yields the closest bandgap to the experiment. The Seebeck coefficient of the studied structure is small due to the overlap of the bands. We show that strain can lower the overlap of the bands but cannot open a gap and improve thermoelectric properties.

Automated summary

Zirconium ditelluride, a layered two-dimensional transition-metal dichalcogenide, shows potential for thermoelectric applications due to its low thermal conductivity and strong spin-orbit coupling. Different exchange-correlation functionals significantly impact the electronic band structure and thermoelectric properties of ZrTe2. While strain can reduce band overlap, it does not improve thermoelectric properties in this case.