Ab. initio study of the structural, elastic, electronic and optical properties of Cu3N

Abstract

Electronic, optical, elastic, properties of Copper nitride (Cu 3 N) in cubic anti-ReO 3 phase have been studied using the full-potential augmented plane waves (FP-LAPW) within density functional theory (DFT) framework. Generalized gradient approximation (GGA), local density approximation (LDA), Perdew-Burke-Ernzerhof generalized parameterization of gradient approximation (GGA-PBE), and new modified Becke and Johnson GGA (MBJ-GGA) have been used for exchange-correlation potentials. The structural properties such as equilibrium lattice parameter, bulk modulus and its pressure derivative have been obtained and optimized. The Hubbard potential has been enhanced to improve bandgap energy. Optical properties, such as the dielectric function, refractive index, extinction index, and optical band gap, were calculated for radiation up to 14 eV. The chemical bonding in Cu 3 N was discussed by three method electronegativity concept, B/G ratio, and charge density distribution. Moreover, Elastic constants, Young's modulus, shear modulus, Poisson's ratio, sound velocities for longitudinal and shear waves, Debye average velocity and Debye temperature have been calculated. The estimated structural, elastic and other parameters are in good agreement with experimental data. The calculation exhibits that Cu 3 N is a direct semiconductor (0.7-1.12 eV) with ductile and ionic identity.

Comment on "Ab Initio Study of the Structural, Elastic, Electronic and Optical Properties of Cu3N" [Materials Research. 2014;17(2):303-310]

“…So, as we see, also there are big differences between our results and those illustrated in Table 1 Recently, Rahmati et al, 1 have published a paper in Materials Research 2014; 17(2): 303-310. They have investigated the structural, elastic, electronic and optical properties of Cu 3 N in its phase cubic anti-ReO 3 structure.…”

“…Firstly, it is to be noted that the numerical value of the density of Cu 3 N material in its phase cubic anti-ReO 3 structure obtained by Rahmati et al, 1 illustrated in Table 1 is wrong. Secondly, because the longitudinal (v l ), transverse (v t ) and average (v m ) elastic wave velocities, and the Debye temperature θ D are directly related to the density (please, see the formulas of equations. (6), (7) and (8) in the Ref.…”

“…(6), (7) and (8) in the Ref. 1 ), so also, the numerical values of (v l ), (v t ), (v m ) and θ D are also wrong.…”

“…The numerical values of the density, the longitudinal (v l ), transverse (v t ), and average (v m ) elastic wave velocities, and the Debye temperature of Cu 3 N material in its phase cubic anti-ReO 3 structure obtained by Rahmati et al, 1 are illustrated in Table 1.…”

“…This error is certainly due to the inaccuracy application of the formula used by Rahmati et al, 1 to calculate the density. So using the lattice parameter and the elastic constants obtained by Rahmati et al, 1 of Cu 3 N material in its phase cubic anti-ReO 3 structure, the right numerical values of the density, the longitudinal (v l ), transverse (v t ) and average (v m ) elastic wave velocities, and the Debye temperature are presented in Table 2.…”