A first-principles investigation of physical properties and superconductivity of NbPS

Abstract

This study reports a theoretical examination of the structural, elastic, mechanical, electronic, phonon and electron-phonon interaction properties of the body-centered orthorhombic structure of NbPS by using the generalized gradient approximation of the density functional theory and the planewave ab initio pseudopotential method. An analysis of the elastic and mechanical properties reveals ductile nature of this compound. The electronic density of states at the Fermi energy is heavily contributed by d orbitals, revealing a more active role for transition metal Nb atoms in determining the lattice dynamical as well as the superconducting properties of NbPS. The phonon spectrum is characterized by anomalies in the lowest acoustic and lowest optical branches which are dominated by the vibrations of Nb atoms. The characteristic features in the electron and phonon spectra clearly suggest that the lowest branches of acoustic and optical nature are more involved in the process of scattering of electrons than the remaining ones due to their phonon anomalies and the significant existence of Nb d electrons at the Fermi level. From the integration of the Eliashberg spectral function, we obtain a value of average electron-phonon coupling constant lambda = 1.07, confirming strong interaction between electrons and phonons. The computed value of superconducting critical temperature T-c = 13.7 K harmonizes very well with the experimentally reported value of 13.0 K.