Ab-initio insights into the mechanical, phonon, bonding, electronic, optical and thermal properties of hexagonal W(2)N(3) for prospective applications.

We thoroughly investigated the structural, mechanical, electronic, vibrational, optical, thermodynamic, and a number of thermophysical properties of W(2)N(3) compound through first-principles calculations using the DFT based formalism. The calculated structural parameters show very good agreement with the available theoretical and experimental results. The mechanical and dynamical stabilities of this compound have been investigated theoretically from the elastic constants and phonon dispersion curves. The Pugh's and Poisson's ratios of W(2)N(3) are located quite close to the brittle/ductile borderline. W(2)N(3) is elastically anisotropic. The calculated electronic band structure and density of states reveal that W(2)N(3) is conducting in nature. The Fermi surface topology has also been explored. The analysis of charge density distribution map shows that W atoms have comparatively high electron density around compared to the N atoms. Presence of covalent bondings between W-N, W-W, and N-N atoms are anticipated. High melting temperature and high phonon thermal conductivity of W(2)N(3) imply that the compound has potential to be used as a heat sink system. The optical characteristics show anisotropy. The compound can be used in optoelectronic devices due to its high absorption coefficient and low reflectivity in the visible to ultraviolet spectrum. Furthermore, the quasi-harmonic Debye model is used to examine temperature and pressure dependent thermal characteristics of W(2)N(3) for the first time.