Electronic and thermoelectric properties of KMgP: A meta-GGA functional within Maximally-Localized Wannier functions basis set Study

In this work, we studied the structural, electronic and transport properties of KMgP using the SCAN functional within the Maximally-Localized Wannier Functions basis set. The structural stability of KMgP in the Matlockite structure of the space group P4/nmm was confirmed through total energy calculations, this is consistent with an experimental work in the literature. The electronic structure reveals the presence of a direct band gap of 2.33 eV. The transport properties, calculated using BoltzWann, show that Seebeck coefficient exceeds 300 $\mu$V/K and remains almost isotropic across the three crystallographic directions, while the electrical and electronic thermal conductivities are higher along the y-direction compared to the x and z directions. Phonon thermal conductivity, estimated using equation of Slack, is below 2 W/m$\cdot$K for temperature values above 100 K. The power factor reaches 8 mW/m$\cdot$K${}^2$ and the figure of merit achieves 0.65 along the y-direction for high n-type doping. These results suggest that KMgP in Matlockite structure offers promising thermoelectric performance, especially along the y-direction.