Merits and limits of the modified Becke-Johnson exchange potential

The first-principles approach based on density functional theory (DFT) and the full-potential linearized augmented plane-wave method were employed to investigate the structural, elastic, electronic and magnetic properties of Na[Formula: see text]NO ([Formula: see text], Sr and Ba) quaternary half-Heusler alloys. The generalized gradient approximation (GGA) as parameterized by Perdew, Burke and Ernzerhof (PBE) and the modified Becke–Johnson exchange potential were used. As far as we know, we present our results which for the first time quantitatively account for the electronic structures and magnetic properties of Na[Formula: see text]NO ([Formula: see text], Sr and Ba) quaternary half-Heusler alloys. From the total energy calculation using three possible atomic configurations ([Formula: see text], [Formula: see text] and [Formula: see text]), it is found that the Na[Formula: see text]NO ([Formula: see text], Sr and Ba) quaternary half-Heusler alloys are more stable in the ferromagnetic [Formula: see text]-phase. From our estimated elastic constants [Formula: see text], it is found that all the considered Heusler alloys are mechanically stable in the [Formula: see text]-phase. We have also investigated the robustness of the half-metallicity with respect to the variation of lattice constants in these alloys. We have found that these alloys are half-metallic ferromagnets (HMFs) with a magnetic moment of 2[Formula: see text][Formula: see text] per formula unit at their equilibrium volumes. The spin-polarized electronic band structure and density of states of these quaternary half-Heusler alloys calculated by GGA (mBJ-GGA) show that the minority spin channels have metallic nature and the majority spin channels have a semiconductor character with half-metallic gaps of 0.49[Formula: see text]eV (2.17[Formula: see text]eV), 0.72[Formula: see text]eV (2.28[Formula: see text]eV) and 0.96[Formula: see text]eV (2.22[Formula: see text]eV) for NaCaNO, NaSrNO and NaBaNO quaternary half-Heusler alloys, respectively. Analysis of the density of states and the spin charge density of these quaternary alloys indicates that their magnetic moments mainly originate from the strong spin-polarization of 2[Formula: see text] states of N atoms and O atoms.

The electronic structure and optical properties of XSi(X = Fe,Ru,Os): A first principles investigation within the modified Becke–Johnson exchange potential plus LDA

Quantitative relations governing the penetration of helium atoms into various types of solids in the course of their plastic deformation in liquid 3He (T = 0.6–1.8 K) and 4He (T = 4.2 K) and dispersion in gaseous helium at 300 K were obtained and analyzed. Experiments were carried out on metals with different lattice types, ionic single crystals, amorphous alloys, and barite and titanium dioxide powders dispersed in helium. Curves illustrating helium extraction from deformed specimens under dynamic annealing were obtained. The temperature range of helium extraction was found to correlate with the melting temperature and the initial and deformed structures of a material, which determine the number and character of helium traps present in the material. The dependence of helium penetration intensity on the type of defects forming under plastic deformation for various materials, as well as the formation of chemical bonds of helium atoms to the defected structure of these materials, is discussed.

This study analyzes how adding europium and transition metals (Cu, Ag, and Au) at a 12.5% concentration to magnesium oxide (MgO) affects its physical characteristics and potential uses. To do so, the full potential linearized augmented plane wave (FP-LAPW) method, based on spin-polarized density functional theory (SP-DFT), is used to derive the results. Wu and Cohen’s generalized gradient approximation (GGA-WC) described the exchange-correlation potential. The modified Becke-Johnson exchange potential (TB-mBJ) was also used to improve the findings of optoelectronic properties. When Eu and TM (Cu, Ag, and Au) impurities are co-doped into the nonmagnetic (NM) semiconductor MgO, the structural optimization results show that the lattice constants increase, and the bulk modulus decreases with increasing the atomic number of transition metals. The resulting dilute magnetic oxides (DMOs) are stable in the spin-polarized ferromagnetic (FM) phase, and the formation energy values confirm their stability in the [Formula: see text] cubic structure, with the lowest value belonging to Eu[Formula: see text]TM[Formula: see text]Mg[Formula: see text]O. Similarly, calculations of electronic properties using the WC-mBJ functional demonstrate that all compounds have an indirect half-metallic bandgap at L-[Formula: see text] equal to 2.53, 2.49, and 1.39 eV for Eu[Formula: see text]Cu[Formula: see text]Mg[Formula: see text]O, Eu[Formula: see text]Ag[Formula: see text]Mg[Formula: see text]O, and Eu[Formula: see text]Au[Formula: see text]Mg[Formula: see text]O, respectively. They have an integer magnetic moment of 6 [Formula: see text]. The density of states shows that at the Fermi level, the 4f-Eu, d-TM, and p-O states give rise to new energy levels. This indicates that the f–p–d hybridization provides this system with its FM properties. Also, these compounds’ dielectric function and absorption spectra are calculated and analyzed to learn more about their optical properties. The results provide insight into the optical behavior of the materials. It is observed that the co-doped compounds exhibit greater optical absorbance than their un-doped MgO counterparts do. This theoretical investigation opens the way to preparing high magnetic moment DMOs using TM and rare earth as dopants suitable for spintronic and UV devices.

The structural, electronic, mechanical and thermodynamic properties of the perovskite oxide BaAmO3 have been predicted using the full-potential linearized augmented plane wave (FP-LAPW) method. The equilibrium lattice constant, bulk modulus and pressure derivative were computed using different exchange correlations. The optimization of structure was carried out in ferromagnetic, anti-ferromagnetic and non-magnetic states, and the compound was found to be stable in the ferromagnetic state. A systematic study on the band structure and density of states was accomplished using generalized gradient approximation (GGA), Hubbard approximation (GGA + U) and modified Becke–Johnson exchange potential (mBJ),and the compound was found to have a half-metallic nature in all the approximations. The calculated total spin magnetic moment was found to be 5 μ B in all the approximations used. The second-order elastic constants, Young modulus, shear modulus, Poisson ratio and anisotropic factor have also been calculated. In order to have a complete understanding of BaAmO3, the thermodynamic properties were studied in the pressure range of 0 to 40 GPa and the temperature range extending from 0 to 600 K.

Structural, electronic and nonlinear optical properties of B3 and B20 compounds: A first-principles investigation within the LDA, GGA and modified Becke–Johnson exchange potential plus LDA

DFT investigation of structural, electronic and optical properties of pure and Er-doped ZnO: Modified Becke-Johnson exchange potential

Comment on “DFT investigation of structural, electronic and optical properties of pure and Er-doped ZnO: Modified Becke-Johnson exchange potential”

We used an ab initio full potential-linearized augmented plane wave technique within the density functional theory to study the structural and optoelectronic properties of Ag2HgSnS4 in a wurtzite-stannite phase. The exchange correlation effects are included through the generalized gradient approximation and modified Becke-Johnson exchange potential. Various physical quantities, such as lattice parameter, bulk modulus, band structure and density of states, are given. Also, we have presented the results of the effective mass for the electrons in the CB and the holes in the BV. We show that the modified Becke-Johnson exchange potential can predict the energy band gap in better agreement with the experiment. In addition the dielectric function and energy-loss function are presented for the energy range of 0-26 eV. The electronic and optical properties indicate that this compound can be successfully used in optoelectronic devices

Electronic and optical properties of CsGeX[formula omitted]M (X ,M = Br, Cl, I) perovskites for solar cell applications: First-principles study using PBE and TB-mBJ potentials

Lattice properties, energy states and optical spectra of MnxGa1−xAs magnetic semiconductors

First-principles investigation of electronic structure and derived structural and magnetic properties of HgTe alloyed with Mn transition metal

Electric field gradient and magnetic hyperfine field in the bulk and surfaces of [formula omitted] compound

The ground-state physical properties of compounds [Formula: see text] [Formula: see text] are investigated using all electron full potential linearized augmented plane wave plus local orbital (FP-LAPW+lo) method. These properties include thermoelectric, optical, electronic and structural properties. The generalized gradient approximation (GGA) due to Wu Cohen (WC) exchange potential for the exchange correlation (XC) effects was used. The modified Becke–Johnson (mBJ) approximation has also been exploited for the precise measurement of XC energy. The stability of crystal structures in tetragonal chalcopyrite phase was determined by calculating the enthalpies of formation. The electronic properties have been studied by plotting the total density of states (TDOS) and partial density of states (PDOS) as well as band structures. These properties show that all compounds have direct band gaps. By exploiting the imaginary part of the dielectric function [Formula: see text], optical properties such as energy loss spectrum [Formula: see text], reflectivity [Formula: see text], extinction coefficient [Formula: see text], refractive index [Formula: see text], optical conductivity [Formula: see text] and absorption coefficient [Formula: see text] were calculated. It can be seen that threshold absorption for all compounds occurs in the lower energy regions of solar spectrum. Thermoelectric properties like figure of merit (ZT), power factor (PF), electrical conductivity [Formula: see text], thermal conductivity [Formula: see text] and Seebeck coefficient [Formula: see text], were also calculated by employing Boltz Trap code. While studying transport properties, [Formula: see text] was found to be comparatively more efficient than [Formula: see text] [Formula: see text] having maximum value of ZT. Therefore, first principle study of these chalcopyrite compounds revels that they are promising materials for photovoltaics in the infrared and visible part of solar energy.

The ground state, electronic and optical properties of the quaternary alloys BexCd1-xTeyS1-y /CdS for modeling quantum well lasers: Ab-initio study within modified Becke-Johnson exchange potential