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First principles study of structural, elastic, electronic and optical properties of Nb 2 N and Ta 2 N compounds
Author(s) -
Chihi T.,
Parlebas J. C.,
Guemmaz M.
Publication year - 2011
Publication title -
physica status solidi (b)
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.51
H-Index - 109
eISSN - 1521-3951
pISSN - 0370-1972
DOI - 10.1002/pssb.201147033
Subject(s) - bulk modulus , refractive index , lattice constant , shear modulus , elastic modulus , materials science , poisson's ratio , condensed matter physics , plane wave , electronic structure , moduli , thermodynamics , poisson distribution , physics , optics , mathematics , diffraction , composite material , quantum mechanics , statistics , optoelectronics
Structural, elastic, electronic and optical properties of hexagonal β‐Nb 2 N and β‐Ta 2 N compounds are studied for different pressures. The computational technique is based on a plane wave pseudo potential (PWPP) method. The exchange correlation is treated using a generalized gradient approximation (GGA). We evaluate ground state quantities such as lattice parameter, bulk modulus and its pressure derivative, as well as elastic constants. The calculated equilibrium lattice is in rather good agreement with experimental data. Elastic constants and their pressure dependence are calculated using a static finite strain technique. We derive bulk and shear moduli, Young's modulus and Poisson's ratio for ideal polycrystalline β‐Nb 2 N and β‐Ta 2 N aggregates. Also, we present results of densities of states. Furthermore, starting from dynamical optical properties, the static dielectric constant ε ( ω = 0) is calculated for both compounds, along with the corresponding static refractive index n (0). The present results are a pioneer quantitative theoretical prediction of elastic, electronic and optical properties in the case of β‐Nb 2 N and β‐Ta 2 N compounds.