Plane Wave Method Research Articles

Half Metallic Properties of the Polymorphs of Rubidium Selenide Compound

Half-metallic ferromagnets denote a specific category of compounds where one spin channel exhibits a gap at the Fermi level, contrasting with the metallic nature of the other spin channel. This distinction results in complete carrier spin polarization, reaching 100% at the Fermi level. A first-principles pseudopotential plane-wave method is utilized to examine the structural, electronic, and magnetic characteristics of RbSe across various polymorphs. Our investigation covers the RbSe compound in the CsCl (B2), NaCl (B1), ZnS (B3), NiAs (B81) and wurtzite (B4) phases. The calculations were done using the quantum ESPRESSO code within the generalized gradient approximation. The lattice parameters, bulk moduli, and their pressure derivatives agrees with prior theoretical data for cubic structures. The electronic band structures and density of states indicate the emergence of half-metallic and magnetic properties in RbSe, which stem from the existence of spin-polarized p orbitals within the Se atom. RbSe shows half-metallic behaviour in all structures studied with an integer magnetic moment of 1μB per formula unit for CsCl, NaCl, ZnS; and 2μB for NiAs and wurtzite. Results showed that most energetically stable phase of all five crystal structures studied is the CsCl-type of RbSe.

High-performance optoelectronic and thermoelectric properties of transparent conductors based on Tl2O3 under pressure

In this work, the full-potential linearized augmented plane wave method (FP- LAPW) and the modified Becke-Johnson (mBJ) functional with spin–orbit (SO) coupling are used the obtain the structural, optoelectronic and thermoelectric properties of Tl2O3 under pressure. The results show that Tl2O3, as transparent conducting oxide (TCO), is a direct bandgap semiconductor with a band gap of 1.23 eV. The band gap value and the effective mass of electrons increases by increasing pressure. Density of state spectra reveal that the nature of electrons in Tl-6s state in the bottom of conduction band, like free electrons in s state, is responsible for the conducting behavior of Tl2O3. A blue shift is observed in optical spectra such as electron energy loss and absorption spectra with an increase in pressure. Obtained dielectric constants under pressure are inversely proportional to the band gap value according to Penn model. The effects of pressure on thermometric properties are also explored. The hydrostatic pressure increases Seebeck coefficient, while it decreases thermal conductivity that is an effective way to the enhancement of the thermoelectric efficiency of TCOs. A figure of merit (ZT) of 0.98 in p-type Tl2O3 is achieved that is desirable for using in thermoelectric devices.

Electronic structure of double perovskite SrTi0.5Co0.5O3: order, disorder, and vacancy effects

In this study, we investigate the electronic structure of the ordered/disordered double perovskite SrTi0.5Co0.5O3 (STCO) using density functional theory (DFT) and the full-potential linearized augmented plane wave method. Detailed structural and magnetic stability analysis revealed that Sr2TiCoO6 crystallizes in the tetragonal I4/m space group, in which Co4+ and Ti4+ ions are distributed in an alternating arrangement along three directions. Notably, Sr2TiCoO6 exhibits a half-metallic property and exhibits ferromagnetic (FM) behavior, originating from the Co4+-O2--Ti4+ bonds and the high spin state of cobalt. Additionally, a chemical/magnetic stability analysis was carried out to identify the ground state structure in disordered STCO. The investigation identified a two-dimensional-like configuration (referred to as STC5FM) characterized by ferromagnetic order. This particular arrangement represents the most chemically stable layered configuration, featuring a maximal occurrence of Co–O–Co chains. Thus, Co4+ ions exhibit an intermediate spin state following Goodenough-Kanamori-Anderson rules of ferromagnetic mechanism. Interestingly, this structure also displays ferromagnetism at room temperature, accompanying with semiconductor properties. The study also explored the impact of oxygen vacancies. Remarkably, the ferromagnetic attributes remain robust even in the presence of oxygen vacancies. Moreover, a transition from semiconductor to metal behavior becomes evident under these conditions.

First-principles quantum computational study to investigate radiation energy-dependent effect on optoelectronic properties of bismuth oxyhalides BiOX (X= I, Br)

Metal oxyhalides are potential candidates for fundamental and technological interest in pharmaceutical, biological, optical, photoluminance, sensing, energy, and photocatalyst applications. In this study, using first-principles density functional quantum computational approach, we investigate the electronic and optical properties of two members of bismuth oxyhalides, BiOX (X = I, Br). The study is mainly aimed to characterize and examine the light radiation energy-dependent optical properties of the compounds by using mBJ desnty functional with the full potential linearized augmented plane wave method. The oxyhalides show indirect bandgap semiconductor nature having bandgaps of 2.2 eV for BiOI and 3.5 eV for BiOBr. Besides, these are p-type materials owing to a large hole-like carrier density of states in the valence bands close to the Fermi level. The energy bands show considerable dispersion of particles. The increasing reflectivity at high light energy shows the potential of the materials as good reflectors in shielding screens or glasses to avoid damage from the ultraviolet radiation.

Electronic transport in nearly compensated half-metallic FeMnGa based-junction

The all-electron full-potential linearized augmented plane-wave method is used to investigate the structural, electronic, and magnetic properties of the cubic C1b FeMnGa. We show that FeMnGa is a spin-gapless semiconductor, and by changing the lattice constant, we obtain a nearly compensated half-metallic ferrimagnet. This makes it suitable for spintronic devices. Then, a combined non-equilibrium Green’s function and density functional theory are used to show that both symmetric and asymmetric FeMnGa/Pd/FeMnGa junctions present infinite giant magneto-resistance, with higher conductance obtained for the symmetric junction with Fe–Pd interfaces.

Effect of bending deformation on the electronic and optical properties of O atoms adsorbed by Be3N2.

In this paper, the optimum coverage of 4.44% and the optimum adsorption sites were determined for the Be3N2 adsorption system of O atoms at different coverages based on density functional theory. The electronic and optical properties of the model were investigated by applying bending deformation to the model at these coverage and adsorption sites. Adsorption of O atoms disrupts the geometrical symmetry of Be3N2, resulting in orbital rehybridization and lowering its band gap. Bending deformation causes the band gap of the adsorbed O atom structure of Be3N2 to first increase and then decrease, resulting in the modulation of its band gap. With increasing bending deformation, the adsorbed system is redshifts, and the degree of redshift increases with increasing bending deformation. All calculations in this paper were performed using the first-principles-based CASTEP module of Materials Studio (MS). The generalized gradient approximation (GGA) plane-wave pseudopotential method and the Perdew-Burke-Ernzerhof (PBE) Perdew et al. Phys Rev Lett 77:3865, 1996 generalized functional were used in the geometry optimization and calculation process to calculate the exchange-correlation potential between electrons. The effect of coverage on the electronic and optical properties of the Be3N2-adsorbed O atom system was investigated by adsorbing different numbers of O atoms on a monolayer of Be3N2. The Be3N2 protocell contains two N atoms and three Be atoms with a space community of P6/MMM (No.191). The original cell was expanded 3 times along the direction of the base vectors a and b in the Be3N2 plane to create a 3 × 3 × 1 monolayer Be3N2 supercell system. A vacuum layer of 15Å is set in the direction of the crystal plane of the vertical monolayer Be3N2 supercell to eliminate interactions between adjacent layers. In the overall energy convergence test of the Be3N2 supercell, the plane wave truncation energy was set to 500eV, and the energy difference between the calculations given in the literature Reyes-Serrato et al. J Phys Chem Solids 59:743-6, 1998 using 550eV was less than 0.01eV, verifying the reliability of the data at a truncation energy of 500eV. The Monkhorst-Pack special k-point sampling method Monkhorst et al. Phys Rev B 13:5188, 1976 was used in the structural calculations, and the grid was set to 3 × 3 × 1. The geometric optimization parameters are set as follows: the self-consistent field iteration convergence criterion is 2.0 × 10-6eV, and the iterative accuracy convergence value is not less than 1.0 × 10-5eV/atom for the total force of each atom and less than 0.03eV/Å for all atomic forces. In addition the high-symmetry k-point path is taken as Γ(0,0,0) → M(0,0.5,0) → K(- 1/3,2/3,0) → Γ(0,0,0) Chen et al, AIP Adv 8:105105, 2018.

Solitons and vortices formation in deformed photonic graphene

We investigate the formation and evolution of two-dimensional solitons and vortices in deformed photonic graphene, encompassing fundamental solitons, multipole solitons, and vortex solitons. Using the plane-wave expansion method, we analyze the bandgap structure of photonic graphene, revealing Dirac cones whose characteristics are influenced by deformation. Soliton generation results from lattice potential deformation, linear energy gap modulation, and nonlinear effects. Specifically, fundamental and dipole solitons, exhibiting out-of-phase behavior, propagate robustly within photonic graphene, maintaining structural integrity over extended distances, while other soliton solutions are unstable. Furthermore, we explore the realization and propagation characteristics of vortex solitons with unit topological charge within photonic graphene.

Coupled Insights into Structural, Electronic, and Optical Properties of GeTMS3(TM=Sc, Fe, Zn) Sulfide Perovskite across Different Phases: Ab Initio Study

The structural stability analysis of various phases of GeTMS3(TM=Sc, Fe, Zn) sulfide perovskite has been conducted utilizing the WIEN2k package. This investigation leverages density functional theory (DFT) within the full potential linearized augmented plane wave (FP-LAPW) method, employing GGA-mBJ potentials. The focus of this study has encompassed the computation of structural, magnetic, and optical attributes across distinct GeTMS3 phases. These materials have been identified as promising contenders for applications in photovoltaics and spintronics. The study reveals the stability of various phases, with the orthorhombic phase proving energetically favorable for GeScS3 and GeZnS3, and the tetragonal phase for GeFeS3. Magnetic analyses indicate favorable ferromagnetic behavior in GeFeS3 and nonmagnetic characteristics in GeScS3 and GeZnS3. Furthermore, electronic examinations unveil semimetallic and semiconducting behaviors in GeScS3 and GeZnS3 in the tetragonal, respectively, with GeFeS3 exhibiting a half-metallic nature in the orthorhombic phase. Optical properties illustrate their potential as light harvesters, displaying characteristics suitable for energy conversion applications. This study contributes to a deeper understanding of sulfide perovskite properties, offering insights into potential applications in diverse technological fields.

First‐principles calculations to investigate structural, electronic, optical, and transport properties of half‐Heusler VFeZ (Z = N and P) compounds

AbstractThis research work investigates the structural, electronic, optical, and thermoelectric characteristics of VFeZ (Z = N and P) half‐Heusler compounds. The study employs the full‐potential linearized augmented plane wave (FP‐LAPW) method integrated into the WIEN2K algorithm, serving as the underpinning framework for density functional theory (DFT) analysis. In the study, we use the PBE generalized gradient approximation (PBE‐GGA) to identify numerous parameters associated with structural and elastic properties. Lattice parameter results are in agreement with previous outcomes. Moreover, computed elastic parameters satisfy the criterion for stability. In the cubic structure VFeZ (Z = N and P) is ductile, to enhance the computations of electronic characteristics, Tran and Blaha's modified Becke‐Johnson potential (TB‐mBJ) is used. Our simulations demonstrate that the materials exhibit semiconductor behavior, with a direct band gap for VFeZ (Z = N and P). Strong UV absorption is found via optical experiments suggest compounds are suitable for optical application. Furthermore, study of the thermoelectric properties suggests its application in the thermoelectric generators.

Wave optical model for tomographic volumetric additive manufacturing

Tomographic Volumetric Additive Manufacturing (TVAM) allows printing of mesoscopic objects within seconds or minutes. In TVAM, tomographic patterns are illuminated onto a rotating glass vial which contains a photosensitive resin. Current pattern optimization is based on a ray optical assumption which ultimately leads to limited resolution around 20 µm and varying throughout the volume of the 3D object. In this work, we introduce a rigorous wave-based optical amplitude optimization scheme for TVAM which shows that high-resolution printing is theoretically possible over the full volume. The wave optical optimization approach is based on an efficient angular spectrum method of plane waves with custom written memory efficient gradients and allows for optimization of realistic volumes for TVAM such as (100μm)3 or (10 mm)3 with 5503 voxels and 600 angles. Our simulations show that ray-optics start to produce artifacts when the desired features are 20 µm and below and more importantly, the amplitude modulated TVAM can reach sub 20 µm features when optimizing the patterns using a full wave model.

Computational investigation on the structural, electronic and optical characteristics of earth-abundant solar absorbers Cu2BeSnX4 (X= S, Se, Te)

This study aims to examine the equilibrium Kesterite structure of Cu2BeSnS4, Cu2BeSnSe4, and Cu2BeSnTe4 by the application of density functional theory (DFT) and the Full-Potential Linearized Augmented Plane Wave (FP-LAPW) method. The study demonstrates that both Cu2BeSnS4 and Cu2BeSnSe4 compounds are semiconductors with direct band gaps at the Γ point, while Cu2BeSnTe4 has an indirect band gap (Γ→X). The electronic and optical characteristics of these materials indicate their potential utility in optoelectronic, photonic, and photovoltaic applications. Furthermore, a thorough comparison has been conducted between the obtained results and other experimental and theoretical data from the same chalcogenide family. In summary, the findings offer valuable information on the possible photovoltaic uses of these compounds.

FP-LAPW study of structural, magnetic, electronic, elastic, and thermoelectric properties of CoCrS Half-Heusler compound

The present article has utilized the WIEN2k computational code to examine the structural, elastic, electronic, magnetic, thermoelectric, and dynamic aspects of the CoCrS Half-Heusler (HH) compound. In this work, calculations have been performed by utilizing the full-potential linearized augmented plane wave method using density functional theory. The electronic bandgap was better interpreted by using the modified Becke–Johnson exchange–correlation functional. We evaluated various electronic properties of the CoCrS HH compound, including band structure plots and density of states. Furthermore, we examined the magnetic characteristics through the computation of magnetic moments and the examination of the spin-polarized electronic state behavior. We also determined the elastic properties of the CoCrS HH compound. These properties, which include stiffness, resilience, and general stability, provide important information about how the material responds to mechanical deformation. Moreover, we explored the electronic structure and found that type 5 of CoCrS exhibits a metallic behavior. In addition, we examined the compound’s thermoelectric properties. Finally, the dynamical properties indicate that type 5 of CoCrS is dynamically stable.

First-principles study of electronic and magnetic properties in site dependent Fe-doped chalcopyrite ZnSnAs2semiconductors: Comparison with those of Mn- and Cr-doped ZnSnAs2

The electronic and magnetic properties of Fe-doped ZnSnAs2 within chalcopyrite structures have been studied by first-principles calculations using the density functional theory (DFT) full-potential linearized augmented-plane-wave method and the plane-wave pseudopotential methods. The band gap of ZnSnAs2 was determined to be 0.816 eV using the modified Beck-Jonson (mBJ) exchange potential. When Fe dopants substitutionally replace Sn atoms, half-metallic ferromagnetism is observed in ZnSnAs2 where in the spin-down band at the Fermi level is entirely unoccupied. The magnetic exchange interaction between two Fe atoms substituting Zn and Sn sites in the supercell with different geometries has been studied. The total energy difference (ΔE) between the antiferromagnetic (AFM) and ferromagnetic (FM) configurations suggests that Fe atom occupation of Zn sites in ZnSnAs2 leads to a predominantly AFM state, while the Fe atom occupation of Sn sites prefers the FM state.

Tunable opto-electronic and thermoelectric response of alkali based half-Heusler semiconductors AMgN (A = Rb, Cs) for sustainable energy: A computational approach

The quick depletion of energy sources and the resulting environmental consequences can be wisely addressed by investigating effective and environmentally friendly materials that have the capacity to convert wasted energy into electricity. This work reports on the thermoelectric features investigations of half Heusler materials, AMgN (A = Rb, Cs). The semi-empirical Boltzmann theory is used alongside the full potential linearized augmented plane wave plus local orbital method (FP-LAPW + lo) to conduct the research. The modified Becke-Johnson (mBJ) exchange potential by Trans-Blaha, the parameterized generalized gradient approximation (GGA) by Perdew-Bruke-Ernzerhof (PBE), and the local density approximation (LDA) proposed by Perdew and Wang (PW) are used to integrate the exchange–correlation energy/potential portion. The electronic band structure results show that RbMgN exhibits a direct energy band gap of 1.35 eV and CsMgN has an indirect energy band gap of 0.66 eV. The optical outcomes reveal that both compounds have absorption in the ultraviolet range, making them suitable for optoelectronic applications. The thermal conductivity,See-beck coefficient, electrical conductivity, power factor, and figure of merit (ZT) are calculated at 300 K, 700 K, and 1200 K temperatures in order to understand their thermoelectric nature. According to our computations, 300 K was the ideal value for the Seebeck coefficient for both materials. The Seebeck coefficient values for RbMgN were found to be better than those for CsMgN. The materials under consideration have the ZT parameter (ZT ∼ 1) calculations for both AMgN (A = Rb, Cs) revealing that all these materials could be useful for the thermoelectric applications and used as alternative green energy resources.

Structural, electronic, magnetic, and optical properties of RE2ZrZnO6 (RE= La, Dy and Ho) double perovskites: experimental and DFT studies

In the present work, density functional theory (DFT) and experimental methods are used to examine the structural, electronic, optical, and magnetic characteristics of the RE2ZrZnO6 (RE = La, Dy, and Ho) double perovskites. The synthesis of these double perovskites oxides is done using the solid-state method. The orthorhombic structures are confirmed by XRD analysis. The EDS mapping shows the presence of La, Dy, Ho, Zr, Zn, and O with their required compositions, SEM images demonstrate the formation of well-shaped particles. On the theoretical side, Full potential linearized augmented plane wave (FP-LAPW) method is employed in the framework WIEN2k code. The half metallic nature of the studied compounds was revealed by spin polarized band structures and density of states. It was found that optical conductivity increases as photon energy increases up to a certain point, beyond the limit it begins to decrease. The comprehensive analysis reveals the studied compounds are potential materials for spintronic applications.

Comprehensive DFT investigation of ternary thallium tetragonal crystals: assessing their viability for solar cell applications

To ascertain the suitability of the TlInX2 (X = S, Se, Te) tetragonal structures for photovoltaic applications, first-principles calculations were carried out using the pseudopotential plane wave method to assess the structural, electronic, elastic, and optical characteristics of the considered compounds via the DFT software CASTEP. For all three compounds, our calculated structural parameters were in excellent agreement with both the experimental and previous theoretical results. Our calculations provided the first predicted elastic constants for the TlInS2, TlInSe2 and TlInTe2 compounds. The three tetragonal systems were mechanically stable and exhibited pronounced and noticeable elastic anisotropy. Analysis of the optical properties revealed that TlInX2 (X = S, Se, Te) exhibited distinct absorption in the ultraviolet radiation range and pronounced optical anisotropy. The calculated bandgap values obtained using the HSE06 hybrid functional were 1.68 eV, 1.38 eV, and 1.36 eV for TlInS2, TlInSe2 and TlInTe2, respectively. These findings are of significant interest because they categorize all three compounds as promising candidates for use in photovoltaic cell applications.

Theoretical investigation of structural, electronic, elastic, and optical properties of rubidium-based perovskites RbSrX3 (X = Cl, Br) for optoelectronic device applications – A DFT study

The search for environment-friendly lead-free halide perovskites is an emerging research area due to their crucial application in the field of photovoltaics and optoelectronics. So, in this current work, the structural, electronic, elastic, thermal, and optical properties of rubidium-based cubic halide perovskites RbSrX3 (X = Cl, Br) are investigated by the full potential linearized augmented plane wave (FP-LAPW) method in the context of density functional theory (DFT). The Generalized Gradient Approximation (GGA) of Perdew-Burke-Ernzerhof (PBE) is implemented as the exchange-correlation potential. The structural stability of these compounds in the cubic phase is studied and the values of their formation energies and ionic filling fraction (IFF) have been assessed. The band structure and DOS plots reveal a wide indirect bandgap at zero pressure. The elastic constants of these compounds are evaluated, and from Blackman's and Every's diagrams, they are found to be elastically stable with a ductile and anisotropic nature. The optical parameters of these compounds imply that they show good response in the ultraviolet region. Thus, by experimentally synthesizing these compounds their potential application in the development of optoelectronic devices working in UV range can be assessed.

First-principles study of the magnetic and optical properties of PtSe2 doped with halogen elements F, Cl, and Br

The electronic structure, magnetic and optical properties of halogen-doped two dimensional PtSe2 are investigated by using the first-principles ultra-soft pseudopotential plane wave method based on density functional theory. It is shown that the doped PtSe2 is more stable under Bottom-Se conditions than under Top-Se conditions, and the higher the doping concentration (C d), the lower the band gap. At C d = 5.56%, the Cl- and Br-doped PtSe2 are transformed from a non-magnetic semiconductor to a magnetic n-type semiconductor with a magnetic moment (M B) of 1 μB; while neither the F-doped PtSe2 nor the pristine PtSe2 is magnetic. When C d = 11.1%, the F-doped PtSe2 at the first neighborhood becomes magnetic metal with M B = 1.39 μB; while that doped at the second nearest neighbor retains a semiconductor with M B = 0. Thus Cl- and Br-doped PtSe2, as well as the first-neighbor F-doped PtSe2 can be well applied in spintronic devices. The optical properties are enhanced for all three doping systems with an obvious peak appearing in the infrared light region. Absorption and reflectivity curve still has a peak in the infrared light region.

First-principles investigation of structural electronic magnetic and thermodynamic properties of CdS alloyed with Co transition metal

This research work investigates the structural, electronic, and magnetic properties of Cd1–xCoxS compounds. The supercells with 16 atoms have been studied by substituting a Cd atom with a Co atom in the cubic unit cell CdS from x = 0 to x = 1 in a Zinc-Blende structure based on the first principles of spin-polarized density functional theory as implemented in the WIEN2k code. The full potential augmented plane wave method FP-LAPW (Full potential linear augmented plane wave) was used in this study to evaluate the structural properties of the compounds, the exchange–correlation term is based on the PBE-GGA (Perdew–Burke–Ernzerhof generalized gradient approximation). For other properties, such as electronic structures, densities of states, and magnetic properties, the TB-mbj GGA (Tight Binding modified Becke–Johnson) exchange potential approximation is utilized. In addition to these properties, the thermodynamic properties were added advantage to clarify their comportment as temperature variation. The analysis of the density of spin-polarized states showed the ferromagnetic character with a from x = 0.125 to x = 0.875. The calculated total magnetic moments of Cd1–xCoxS are addressed concerning the change in lattice parameters. To track the shift brought on by adding Co, we ran our calculationsfrom x = 0.125 to x = 0.875 for Cd1–xCoxS compounds. Hence, the negative energyformation indicates that our compound can be made experimentally. The material may be used for solar cell applications. In summary, our findings represent a guide for future research. The findings of this work might provide useful direction for the usage of this alloy system in a variety of device applications, For example in high-efficiency tandem solar cells, magnetic sensors, and photoconductive detector applications.

Effect of SB Addition on Mechanical Electronic and Thermodynamic Properties of Intermetallic B2-NIAL: First Principles Study

Abstract This study investigates the mechanical, electronic, and thermodynamic properties of B2 NiAl alloyed with Sb, ranging from 0% to 100%. The calculations were conducted using the WIEN2k code based on the full potential linearized augmented plane wave (FP-LAPW) method within the density functional theory (DFT) framework. Generalized Gradient Approximation (GGA) was employed to approximate the exchange-correlation energy. Our analysis of formation enthalpy indicates a preference for Sb to substitute Al sites. Furthermore, we have observed that the mechanical properties of NiAl can be enhanced by adjusting the chemical composition of Sb. Specifically, an increase in antimony content from 0% to 75% results in a notable improvement in ductility tensile, elevating it from 1.92 to 10.72. Conversely, this alteration diminishes the material’s strength. Moreover, both the band structures and density of states (DOS) indicate the metallic behavior exhibited by all NiAl1-xSbx compounds. In addition, we employ the Gibbs2 code to calculate thermodynamic properties, shedding light on the influence of temperature and pressure on the volume, heat capacity, Debye temperature and entropy S of NiAl1-xSbx.