A DFT Study of Structural, Electronic, Optical, and Thermoelectric Properties of TMX (TM = Mo and W; X = N, P, and As) Compounds

Structural, electronic, optical, thermoelectric ,and elastic properties of Mo- and W-based group-V compounds, TMX (TM = Mo and W; X = N, P, and As) have been studied by using the full-potential linear augmented plane wave method. Local spin density approximation (LSDA) has been used for exchange-correlation potentials. Pressure-dependent lattice constants and bulk moduli have been obtained using LSDA. Volume optimization, with and without spin-polarization, reveal that the WC-type hexagonal phase (MoN, MoP, and WN) and MoAs and WP in MnP-type orthorhombic phase are energetically stable in a non-magnetic phase. The electronic properties show that all these materials are metallic in nature, while the optical properties showed high reflectivity and low transmission. The thermoelectric properties have also been elaborated, and, as these materials have zero band gap values, they showed high thermal conductivity at high temperatures with low Seebeck and almost constant electrical conductivity. Moreover, the elastic properties of these two phases are surprising with their high bulk and shear moduli. All the materials fall in the category of super-hard materials with ductile and brittle characteristics.