Full Potential Linearized Augmented Plane Wave Research Articles

DFT and Monte Carlo study of the structural, mechanical, electronic, magnetic and magnetocaloric properties of the Co2VGa Heusler alloy

We determined the structural, mechanical, electronic and magnetic properties of the Co2VGa by using full-potential linearized augmented plane-wave (FP-LAPW) method and Monte Carlo simulation. The structural stability studies were performed for nonmagnetic, ferromagnetic and antiferromagnetic states. The elastic parameters and their derivatives have been calculated. The investigated energy band structure shows that the Co2VGa is half metallic. The total magnetic moments, stiffness constant of spin wave and the Curie temperature are also calculated. The magnetocaloric effect of this material are studied using the results obtained by FP-LAPW. The transition temperature, magnetic entropy change and relative cooling power are calculated.

Fundamental Physical Properties of Nontoxic Tin‐Based Formamidinium FASnX3 (X = I, Br, Cl) Hybrid Halide Perovskites: Future Opportunities in Photovoltaic Applications

To analyze potential alternatives, the fundamental physical properties such as structural, electronic, optical, elastic, thermoelectric, and thermodynamic parameters of tin‐based formamidinium FASnX3 (X = I, Br, Cl) hybrid halide perovskites by using density functional theory are investigated. The calculated results indicate that these compounds exhibit analogous band gap, considerable thermal and elastic stability, and notable optical properties with high dielectric constant and absorption coefficient, significant hole, and electron conductive behavior. The present research work shows as good absorbers for perovskite solar cells, adding to the validity of FP‐LAPW (full‐potential linearized augmented plane wave) methods, simultaneously enhancing the understanding of these practical hybrid perovskite materials. It may be believed that this study will be of a lot of credit for experimentalists for synthesis and characterization of these materials and will be done experimentally in future times due to the very good properties of photovoltaic applications.

First-principles calculations to investigate structural, mechanical, electronic, magnetic and thermoelectric properties of Ba2CaMO6 (M=Re, Os) cubic double perovskites

Structural, mechanical, electronic, magnetic and thermoelectric characteristics of Ba2CaMO6 (M = Re, Os) double perovskites have been calculated using first-principle based full-potential linearized augmented plane wave (FP-LAPW) approach. Optimized ground-state lattice constants of the compounds are in fair resemblance with the respective available experimentally investigated data. Calculated elastic constants and moduli show mechanical stability, anisotropy, ductility and significant stiffness. Computed spin-polarized electronic properties with a diversity of exchange-correlation potential schemes have revealed their half-metallic nature. Estimated spin magnetic moments indicate their ferromagnetic nature with major contributions from the 5d state of transition elements Re and Os. The present study has projected both the perovskite compounds as prospective magnetic materials for a variety of half-metallic, ferromagnetic and spintronic applications. Calculated thermoelectric parameters have predicted their scope of thermoelectric applications in high temperature waste heat management.

First principles study of the structural, elastic, electronic and optical properties of the ternary alloys Ca0.75Zn0.25S and Ca0.75Zn0.25Se

In this paper we present and discus the structural, elastic, electronic and optical properties of the new ternary alloys Ca0.75Zn0.25S and Ca0.75Zn0.25Se in NaCl (B1) structure using the full potential-linearized augmented plane wave (FP-LAPW) method which is based on the density functional theory (DFT). To perform the structural and elastic calculations, we have used the Wu-Cohen generalized gradient approximation (WC-GGA) as exchange-correlation potential while for the electronic and optical properties, Tran-Blaha modified Becke-Johnson(TB-mBJ) scheme is employed. The study is focused on the variation of a number of properties of binary compounds CaS and CaSe when they are doped with 25% of zinc (Zn). For binary compounds, a good agreement is obtained for most of the properties calculated in this work and those measured experimentally. This study is the first prediction of the structural, elastic electronic and optical properties of ternary alloys Ca0.75Zn0.25S and Ca0.75Zn0.25Se. Both these ternary alloys are mechanically stable and present a semiconducting behavior with a direct band gap contrary to the parent binary compounds CaS and CaSe which have an indirect band gap. Therefore, fast and efficient optoelectronic devices might be manufactured by these new ternary alloys.

Electronic structure and optical response of double perovskite Rb2NaCoF6 for optoelectronic devices

The bonding nature, structural, electrical, and optical properties of Rb2NaCoF6 has been investigated using density functional theory (DFT) calculations in this communication. The results are based on the total energy calculations using density functional theory by employing the Full-Potential Linearized Augmented Plane Wave (FP-LAPW) approach. A direct band gap of 1.5eV is observed along (X−X) points with generalized gradient approximation (GGA). The improvement in the band gap i.e. 2.2eV is achieved with modified Becke-Johnson potential. The total and partial density of states shows a good agreement with the band structure. The bonding nature of the compound is studied with a contour plot of electron density. Further emphasis has been given to Rb2NaCoF6 hexaflouroperovskite absorption and reflection spectra, which reveal substantial absorption and reflection in the ultraviolet region. From the current work in Rb2NaCoF6, it is expected that the numerous quantum mechanical phenomena would be able to provide a better understanding in designing the practical devices.

Determination of structural stability, elastic, thermal and half metallic behavior of CoZrVZ (Z = Al, Ga, In, Sn) quaternary Heusler alloys: A DFT study

Physical characteristics of new quaternary Heusler alloys (QHAs) CoZrVZ (Z = Al, Ga, In, Sn) are determined employing first-principles calculations. Perdew-Burke-Ernzerhof (PBE) exchange and correlation functional treated with generalized gradient approximation (GGA) within full potential linearized augmented plane wave (FP-LAPW) method. Structural parameters are obtained through geometry optimization process for three non-equivalent configurations and Type I is found the most stable. Calculations for magnetic phases i.e. ferromagnetic (FM), anti-ferromagnetic (AFM) and non-magnetic (NM) are performed. Elastic, thermal and magnetic properties are investigated. All alloys are half-metallic (HM) in nature and magnetic moments are in well agreement to Slater-Pauling rule. The estimated Curie temperature (Tc) is well above the room temperature. The mechanical parameters confirmed that all alloys except CoZrVSn are stable and have ductile nature. Thermal properties predicted that all alloys have high melting temperature (Tm). All determined characteristics envisaged that these QHAs are suitable for technological and spintronic applications.

First-principles study of electronic structures, thermodynamic, and thermoelectric properties of the new Rattling Full Heusler compounds Ba2AgZ (Z = As, Sb, Bi)

The ab initio calculations based on the density functional theory (DFT) using the self-consistent Full potential linearized augmented plane wave (FPLAPW) method were performed to explore the electronic structures, thermodynamic and thermoelectric properties of new rattling Full Heusler alloys Ba2AgZ (Z = As, Sb, Bi). Results showed that the AlCu2Mn-type structure state is energetically the most stable structure. The results show that the electronic property of these cubic Rattling Heusler alloys have a semiconducting behavior with indirect band gaps Eg (L-D). The predicted band gaps were found to be 0.566, 0.548 and 0.433 eV for Z = As, Sb and Bi, respectively. The thermodynamic properties comprising the thermal expansion coefficient, heat capacity, entropy and Debye temperature parameter were evaluated at various pressures from 0 to 15 GPa. Thermoelectric properties of the Ba2AgZ (Z= As, Sb, Bi) materials are additionally computed over an extensive variety of temperature and it is discovered that all compounds exhibit ultralow thermal conductivity, good Seebeck coefficients and large high power factors, thus resulting they are suitable for use in thermoelectric device applications.

Unraveling Site Selective Magnetic Properties of Cobalt Sites in Critical Elements Lean RE(TM)5 Magnet Materials

We report here our discovery of crystallographic and interstitial sites and onsite electron correlation propelled intrinsic and derived permanent magnetic properties of critical elements lean RE(TM)5 (RE = La, Ce and TM = Fe, Co) magnet materials. A full potential linearized augmented plane wave (FP-LAPW) method within the local density approximation (LDA) is used to investigate and analyze the electronic structure and magnetism of these RE(TM)5 type structures. To better correlate the experimental results, the effective Coulomb (U) and exchange (J) interactions (Hubbard parameters) are crucial at the transition metal sites. Results show that the main propeller of magnetic anisotropy in these compounds is the cobalt atoms at the 2c sites not the 3g sites. This site-specific property and site preference energetics are used to replace 3g sites with non-critical elements such as iron that exhibits a larger magnetic moment. Based on this strategic replacement, we predict two new compounds that have a larger hardness parameter with a relatively large energy product due to the atomic dilution caused by interstitial addition of nitrogen in the compounds: CeCo2Fe3N2 and LaCo2Fe3N2.

Ab initio prediction of enhanced thermoelectric performance from bulk to monolayer Sb2S2Te

By using the first principles investigations based on the full potential linearized augmented plane wave (FP-LAPW) method within both the generalized gradient approximation (GGA) and the Tran-Blaha modified Becke-Johnson (TB-mBJ), we predicted the electronic structure and thermoelectric properties of bulk and monolayer Sb2S2Te. Both monolayer and bulk structures of Sb2S2Te are semiconductors with an indirect band gap. The band gap can be improved with TB-mBJ. The effect of charge carriers concentration on the electrical conductivity (σ) and the electronic thermal conductivity (κeκe) for bulk Sb2S2Te has reached the level of saturation. The monolayer Sb2S2Te exhibits superior thermoelectric properties and plays a key role in the enhancement of the figure of merit for p-type doping in comparison to the bulk compound. Monolayer Sb2S2Te have ultra-low lattice thermal conductivity and larger thermoelectric (TE) figure of merit ZT. The results demonstrate that the monolayer Sb2S2Te could be potential candidate for TE applications, which has promising TE properties in p-type system.

Accurate Prediction of Band Structure of FeS2: A Hard Quest of Advanced First-Principles Approaches.

The pyrite and marcasite polymorphs of FeS2 have attracted considerable interests for their potential applications in optoelectronic devices because of their appropriate electronic and optical properties. Controversies regarding their fundamental band gaps remain in both experimental and theoretical materials research of FeS2. In this work, we present a systematic theoretical investigation into the electronic band structures of the two polymorphs by using many-body perturbation theory with the GW approximation implemented in the full-potential linearized augmented plane waves (FP-LAPW) framework. By comparing the quasi-particle (QP) band structures computed with the conventional LAPW basis and the one extended by high-energy local orbitals (HLOs), denoted as LAPW + HLOs, we find that one-shot or partially self-consistent GW (G 0 W 0 and GW 0, respectively) on top of the Perdew-Burke-Ernzerhof (PBE) generalized gradient approximation with a converged LAPW + HLOs basis is able to remedy the artifact reported in the previous GW calculations, and leads to overall good agreement with experiment for the fundamental band gaps of the two polymorphs. Density of states calculated from G 0 W 0@PBE with the converged LAPW + HLOs basis agrees well with the energy distribution curves from photo-electron spectroscopy for pyrite. We have also investigated the performances of several hybrid functionals, which were previously shown to be able to predict band gaps of many insulating systems with accuracy close or comparable to GW. It is shown that the hybrid functionals considered in general fail badly to describe the band structures of FeS2 polymorphs. This work indicates that accurate prediction of electronic band structure of FeS2 poses a stringent test on state-of-the-art first-principles approaches, and the G 0 W 0 method based on semi-local approximation performs well for this difficult system if it is practiced with well-converged numerical accuracy.

Computational study of the structural, elastic, electronic and thermoelectric properties of the orthorhombic perovskite CaIrO3 compound

The first principles analysis of structural, elastic, electronic and thermoelectric properties of Calcium Iridium perovskite CaIrO3 compound have been reported. We made our calculations within the full-potential linearized augmented plane wave (FP-LAPW) method, based on Density Functional Theory (DFT) within GGA-PBEsol and GGA-PBEsol with the co-operative effect of spin–orbit coupling correction for exchange-correlation potentials. The calculated structural properties, namely the equilibrium lattice parameters and cell volume, are in good agreement with available experimental data. All single crystal elastic constants are computed, from which values of shear, bulk, Young's modulus and Poisson's ratio for CaIrO3 are calculated using Voigt and Hill approximations. It's found that CaIrO3 compound is ductile and has greater anisotropy in (100) plane. The electronic transport properties at room temperature are obtained via Boltzman transport theory, the Hall coefficient exhibited a sign change as a function of temperature, indicates that the perovskite CaIrO3 is semimetal. Therefore, CaIrO3 is n-type material. The electronic band structure calculations indicate the presence of Dirac point around the Fermi level between the directions (Y-Γ).

Ab initio prediction of thermoelectric performance of monolayer transition-metal nitride halides MNBr (M = Zr, Hf)

Accurate descriptions of the structure, electronic properties and thermoelectric (TE) properties of transition-metal nitride halides MNBr (M = Zr, Hf) monolayers are calculated using the full-potential linearized augmented plane-wave (FP-LAPW) method within both generalized gradient approximation (GGA) and Tran–Blaha modified Becke–Johnson (TB-mBJ) approximation. The band structure shows that all MNBr monolayers are semiconductors with indirect band gaps. The band gap, calculated by TB-mBJ, is larger than that of GGA for both considered compounds. The charge-carrier effective mass increases when going from ZrNBr to HfNBr because of the extra peak of the density of states profile of monolayer HfNBr in the valence band around −0.5 eV, suggesting that ZrNBr should have higher electrical conductivity and HfNBr should have higher Seebeck coefficient. Meanwhile, the monolayered structure of MNBr has intrinsic low lattice thermal conductivity. The results demonstrate that monolayer MNBr has interesting TE properties with n-type doping.

Investigation of optoelectronic and thermoelectric properties of InAsBi for LWIR applications: A first principles and k dot p study

Systematic study on the incorporation effect of dilute Bismuth (Bi) in zinc blende (ZB) phase Indium Arsenide (InAs) is performed taking the full-potential linearized augmented plane wave (FPLAPW) basis sets, the Perdew-Burke-Ernzerh of generalized gradient approximation (PBEsol) exchange correlation (XC) functional, Modified Becke-Johnson (mBJ) potential in the density functional theory (DFT) computation and valence band anticrossing (VBAC) model. Comparatively larger atomic sized Bi impurity in InAs leads to increment in the lattice constant, non-linear reduction of bulk modulus, decrease the bandgap by 31.17 meV/Bi%, and increase the spin-orbit coupling splitting energy (ΔSO) by 18.35 meV/Bi%. A consistent redshift in the optical spectra towards the > 3 μm region is observed for increasing Bi concentration, which makes InAs1-xBix a suitable candidate for the atmospheric infrared transmission windows at 3–5 and 8–12 μm. A reasonably higher value ofΔSOcompared to the direct bandgap mitigate the Auger like non-radiative recombination losses in LASERs and Photodetectors. Computed thermoelectric properties like Seebeck coefficient and electrical conductivity reflects the superiority of Bi incorporation in InAs. Nevertheless, Bi impurity leads to reduction in carrier effective mass in InAs1-xBix, which opens up the possibility to utilize it in High Electron Mobility Transistors (HEMTs) devices.

Theoretical approach to explore structural, electronic, magnetic, elastic and thermal characteristics of Heusler alloys CoYTiZ (Z = Al, Ga, Si, Ge)

In this study, structural, electronic, magnetic, elastic and thermal properties of Co-based Quaternary Heusler alloys (QHAs) CoYTiZ ([Formula: see text], Ga, Si, Ge) have been investigated by Wien2k code. The calculations have been performed using full-potential linearized augmented plane wave (FP-LAPW) method. Generalized Gradient Approximation (GGA) method has been adopted. Structural properties have been explored for three different Wyckoff positions. From the geometry optimization calculations, it is concluded that all these alloys are stable in Type-III crystal structure. Moreover, magnetic phase optimization revealed ferro-magnetic (FM) phase as stable one. Results of electronic properties have shown metallic character for CoYTiAl, CoYTiGa, CoYTiGe while nearly half metal (HM) character for CoYTiSi. Magnetic moment obeys Slater Pauling rule (SP) for these alloys. To check out the mechanical stability, elastic properties have been investigated. Elastic parameters have shown the ductile nature of these alloys. The values for melting temperature ([Formula: see text] have confirmed the thermal stability of the studied alloys.

Structural, electronic, magnetic and mechanical properties of three LaMnO3 phases: Theoretical investigations

First principles density functional theory is used to study the physical properties of LaMnO3 in its orthorhombic (Pnma), cubic (Pm-3m) and rhombohedral (R-3c) phases, using Full Potential Linearized Augmented Plane Wave (FP-LAPW) method implemented in the WIEN2k code. The exchange-correlation potential was treated with the WC-GGA + U approximation (where U is the Hubbard Coulomb energy term) for the calculation of the structural, electronic and magnetic properties, whereas the Tran-Blaha modified Beck-Johnson (TB-mBJ) potential is applied for the calculation of the electronic properties. We also used the ABINIT code to calculate mechanical properties. Our structural, electronic and magnetic calculations obtained are in good agreement with experimental ones. At equilibrium, spin polarization of the orthorhombic phase of LaMnO3 compound is antiferromagnetic (AFM) and we predict the ferromagnetic phase of the compound LaMnO3 to be half-metal with spin polarization of 100%. In addition, the bonding nature reveals a mixture of covalent and ionic bonding character. The ductility and brittleness are explored from mechanical properties, such as elastic constants, bulk modulus, shear modulus, Young's modulus, Poisson coefficient, B/G ratio and anisotropy ratio, and our obtained values indicate that LaMnO3 is a ductile and anisotropic material in the three phases. We have also investigated the elastic wave velocity and Debye temperature to collect more information on mechanical stability.

Magnetic properties and half metallic behavior of the Full-Heusler Co2FeGe alloy: DFT and Monte Carlo studies

The study of structural, electronic and magnetic alloy properties of the full-Heusler Co2FeGe has been undertaken using the first principle method based on the density functional theory (DFT). In this work, we have predicted and underlined the mechanism of the half-metallic behavior of the full-Heusler Co2FeGe alloys by using the Monte Carlo simulations. We have used the full potential linear augmented plane wave (FPLAPW) method as implemented in the Wien2K code to forecast the electronic and magnetic properties of the studied system. We have used the generalized gradient approximation GGA for the treatment of exchange energy and correlation. We have also taken into account the strong correlations orbital of Co and Fe atoms by applying the GGA ​+ ​U approximation founded on DFT ​+ ​U. The GGA ​+ ​U gives a good result showing that compound Co2FeGe is a half-metallic ferromagnetic (HMF) through a large gap of 1.20 ​eV. The value of the magnetic moment is used as input to calculate the magnetic parameter of this alloy when using the Monte Carlo simulations. By the help of the proposed model the temperature dependency of the magnetization, the susceptibility and the specific heat, is studied. The phase transition is of second order type at the critical temperature point. This temperature is in good agreement with the available experimental data.

Structural, Electronic, Magnetic Properties and Elastic Anisotropy of New Ferromagnetic Cu2CrZ (Z=Si and Ge) Full Heusler Alloys

In this paper, we have performed a first-principles study to investigate the electronic structure, magnetic, mechanic and anisotropic elastic properties of Cu2CrZ (Z=Si and Ge) Full Heusler alloys. The study of these characteristics shows thermodynamic and mechanical stability with cubic symmetry in our compounds and they also have an anisotropic character. The ground-state parameters, i.e., lattice constant, the bulk modulus and the electronic structure are calculated using the full-potential linearized augmented plane wave (FP-LAPW) approach to the density functional theory (DFT) within the generalized gradient approximation (GGA+WC) for the exchange and correlation potential. The objective is to seek stable metallic ferromagnet materials.

Optoelectronic properties of solar cell materials based on copper-zinc-tin-sulfide Cu2ZnSn(SxTe1-x)4 alloys for photovoltaic device applications

Cu2ZnSnS4 (CZTS), a quaternary material formed of Earth-abundant elements, is promising in thin-film solar cell devices, as absorbing layer. The high efficiency of solar energy conversion (>12%) recorded in chalcogen-doped Cu2ZnSnS4 renders it an attractive material for the analysis of the structural stability, electronic band structures, and optical characteristics of Cu2ZnSn(SxTe1-x)4 alloys (0 ≤ x ≤ 1) by first-principles calculations. By employing full-potential linearized augmented plane-wave (FP-LAPW) methodology, the acquired results indicate that CZTS and Cu2ZnSnTe4 (CZTTe) parent compounds possess wide and narrow direct band gaps, respectively. The optical characteristics of Cu2ZnSn(SxTe1-x)4 alloys and their bulk counterparts were computed in terms of the complex dielectric function, which allows the examination of the optical absorption, reflectivity, and refractive index of these ultimate alloys. It is inferred that the S/Te compositional ratio in Cu2ZnSn(SxTe1-x)4 has a significant influence on the optical absorption of electromagnetic radiation in the visible to the infrared (IR) regimes. Our results indicate that the increase of Te concentration leads to a red shift of the major feature peaks in the optical absorption spectra. Because of their direct band gap and remarkable optical absorption, Cu2ZnSn(SxTe1-x)4 alloys with S/Te compositional ratios under 0.5 could be useful materials in thin-film solar cell devices, as absorbing layers. This theoretical report is expected to provide relevant information for future experimental works involving the design of novel solar cell materials based on CZTST systems.

Investigation of electronic, optical and thermoelectric properties of perovskite BaTMO3 (TM=Zr, Hf): First principles calculations

The structural, electronic, optical, and thermoelectric characteristics of crystalline oxides-perovskites BaTMO3 (TM=Zr or Hf) were investigated using the all-electron full-potential linearized augmented plane wave (FP-LAPW) method within the framework of density functional theory (DFT). The generalized gradient approximation as parameterized in Perdew, Burke, and Ernzerhof (PBE-GGA) was employed to calculate exchange-correlation potential. Also, the modified Becke Johnson exchange potential approximation as parameterized by Tarn and Blaha (TB-mBJ) was used to improve the bandgap estimation. According to our calculations, both perovskites BaZrO3 and BaHfO3 show insulator behavior and have widely indirect band-gap energy (R-Γ) 4.42 (3.39) eV for BaZrO3 and 5.25 (3.69) eV for BaHfO3 from both approaches, TB-mBJ (PBE-GGA), respectively. The optical properties such as dielectric tensor, the refractive index, the absorption coefficient, and the electron loss function have been calculated and analyzed. The optical transitions mainly take place if an electron radiate from the initial state O-2p to the final state Hf-5d or to the Zr-4d in BaHfO3 or BaZrO3 case, respectively. Furthermore, the transport characteristics calculations based on semi-classical Boltzmann theory have been discussed. The thermopower at RT of both compounds BaHfO3 and BaZrO3 are 260.47 and 208.33 μV/K, respectively. This result is good enough to consider these materials as promise thermoelectric candidates. Our results were compared with the previous ab intio calculations and experiments and showed a reasonable agreement.

Structural, diffuse reflectance and luminescence study of t-Mg2B2O5 nanostructures.

We report here the structural, reflectance, photoluminescence and thermoluminescence study of t-Mg2B2O5 nanostructures synthesized using optimized combustion method relatively at much lower temperature. The rietveld refinement of X-ray diffraction data confirms single-phase triclinic crystal structure of Mg2B2O5 nanoparticles. The direct band gap determined using diffuse reflectance spectra (DRS) was 5.23 eV, which is contrary to earlier reports quoting Mg2B2O5 as indirect band gap material. To elucidate the nature of band gap in Mg2B2O5, we performed first principle calculations based on full potential linearized augmented plane-wave (FPLAPW) method, predicting the direct band gap of 5.10 eV in t-Mg2B2O5 which is in good agreement with our experimental results. The t-Mg2B2O5 nanoparticles were found to exhibit yellow-reddish photoluminescence peaking at 588 nm, attributed to various defects states. The combustion synthesized Mg2B2O5 nanocrystals exhibited ultraviolet (254 nm) responsive thermoluminescence (TL). TL glow curve of Mg2B2O5 comprises of one dominant peak around 417–428 K and less intense shoulder around 573–589 K which arouse possibility of various trapping sites or defects present in the sample. The TL analysis using general order Kitti’s equations was performed to estimate the activation energies of trapping states. Owing to already well-known mechanical and thermal properties, the direct wide band gap nature and UV responsive thermoluminescence of combustion synthesized t-Mg2B2O5 nanostructures can pave way for its use in luminescence-based applications and UV dosimetry. As an additional application of Mg2B2O5, anti-biofilms activity of Mg2B2O5 nanoparticles using pseudomonas aeruginosa bacterial cells was also performed which revealed 91 ± 2.7% inhibition of biofilms formed by P. aeruginosa, respectively, at 100 μg/ml after 24 h of treatment.