Cohesive Energy Calculations Research Articles

Bandgap Characteristics of Boron-Containing Nitrides—Ab Initio Study for Optoelectronic Applications

Hexagonal boron nitride (h-BN) is recognized as a 2D wide bandgap material with unique properties, such as effective photoluminescence and diverse lattice parameters. Nitride alloys containing h-BN have the potential to revolutionize the electronics and optoelectronics industries. The energy band structures of three boron-containing nitride alloys—BxAl1−xN, BxGa1−xN, and BxIn1−xN—were calculated using standard density functional theory (DFT) with the hybrid Heyd–Scuseria–Ernzerhof (HSE) function to correct lattice parameters and energy gaps. The results for both wurtzite and hexagonal structures reveal several notable characteristics, including a wide range of bandgap values, the presence of both direct and indirect bandgaps, and phase mixing between wurtzite and hexagonal structures. The hexagonal phase in these alloys is observed at very low and very high boron concentrations (x), as well as in specific atomic configurations across the entire composition range. However, cohesive energy calculations show that the hexagonal phase is more stable than the wurtzite phase only when x > 0.5, regardless of atomic arrangement. These findings provide practical guidance for optimizing the epitaxial growth of boron-containing nitride thin films, which could drive future advancements in electronics and optoelectronics applications.

Insights into novel MAX phases based on Mo2SiX (X = C, N) from first-principles calculations

Our present study reports the physical properties of the new MAX phases belonging to the 211-family, specifically Mo2SiX (X = C, N). The physical properties calculations for these MAX phases were conducted using the first-principles approach. The cohesive energy calculations for Mo2SiC and Mo2SiN revealed significant values of 6.57 eV and 5.94 eV, respectively, indicating the remarkable stability of these compounds and the presence of robust bonding among their constituent atoms. The investigated compounds showed metallic properties like other MAX phases. Interestingly, both MAX phases demonstrated non-magnetic behavior, attributed to their symmetrical electronic structures for up and down spin states. Additionally, we observed that these compounds exhibited optical refraction values exceeding 1 for infrared, visible, and UV light (energies below ∼ 10 eV). However, beyond 10 eV, they become less than 1 in response to higher-energy light. Furthermore, we comprehensively evaluated the absorption and reflection characteristics of these compounds. These results offer insightful information about the behavior of the Mo2SiX (X = C, N) for various advanced technological applications.

Unlocking the potential of Mg-ion batteries: Cu2C MXene anode with ultrahigh storage and energy density with rapid Mg diffusion

Magnesium-ion batteries hold immense promise for the future of electrical energy storage due to the abundant availability of magnesium metal and the efficient energy storage capacity of divalent magnesium ions which has the potential to revolutionize both large-scale stationary applications and portable devices. MXenes, encompassing transition metal carbides/nitrides/carbonitrides, are still considered newcomers in the domain of 2D nanomaterials, especially regarding their utilization in energy storage applications. In this work, we employed first principles based DFT calculations to comprehensively evaluate the electrochemical behavior of 2H phase Cu-based MXene (Cu2C) monolayer as promising anode material for Mg-ion batteries. The stability of the Cu2C monolayer was assessed through calculations of negative cohesive energy, positive phonon frequencies, and AIMD simulations to confirm stability at room temperature along with superior mechanical strength. The simulation outcomes show that strong affinity for Mg ions to the Cu2C monolayer, which is attributed to metallic character, suggesting good electronic conductivity and aslo, the calculated negative adsorption energy of −1.25 eV, indicating a favorable interaction for potential battery applications. The Cu2C monolayer emerges as a compelling candidate for anode materials due to its exceptional combination of high theoretical specific capacity (1541.36 mAh/g) and a low average operating voltage (0.50 V). This translates to a remarkable energy density of 2882.34 mWh/g (referenced against the standard hydrogen electrode potential), making it a strong contender for next-generation battery technologies. Furthermore, our investigation revealed rapid diffusion barriers for Mg-ion migration with exceptional properties with robust compatibility with electrolytes, makes it anode materials for Mg-ion batteries, attracting significant interest in the near future.

Hydrogen and fluorine substituted graphyne and graphdiyne sheets: Exploration of electronic and optical properties using density functional theory

This study delves into the geometrical structure, electronic characteristics, and optical properties of hydrogen (H) and fluorine (F) substituted graphyne (GY) and graphdiyne (GDY) sheets using density functional theory (DFT). The investigated sheets are denoted as R-GY and R-GDY, where R represents either H or F. Our results reveal the energetic stability of these sheets through cohesive energy calculations and confirm their thermal stability via ab-initio molecular dynamics (AIMD) simulations. It is found that R-GY and R-GDY sheets are semiconductors. The optical characteristics of H-substituted sheets closely resemble those of F-substituted ones. The findings showcase the strong light-absorbing capabilities of R-GY and R-GDY sheets in the visible and ultraviolet regions, making them favorable materials for applications in photovoltaic systems and ultraviolet absorbers. The reflection and transmission coefficients indicate the high transparency of the sheets for light. Our findings could enhance the understanding of the electronic and optical properties of R-GY and R-GDY, potentially inspiring researchers to develop optoelectronic devices utilizing these materials.

DFT Study on the Janus ZrSSe Monolayer for Its Potential Application in NO Gas Sensing.

The growth of industry has resulted in increased global air pollution, necessitating the urgent development of highly sensitive gas detectors. In this work, the adsorption of the Janus ZrSSe monolayer for CO, CO2, NH3, NO, NO2, and O2 was studied by first-principles calculations. First, the stability of the ZrSSe monolayer is confirmed through calculations of cohesive energy and AIMD simulations. Furthermore, the calculations indicate that the Se layer exhibits higher selectivity and sensitivity toward gas molecules compared to the S layer. Specifically, among the gases adsorbed on the Se layer, NO has the shortest adsorption distance (1.804 Å), the lowest adsorption energy (-0.424 eV), and the greatest electron transfer (0.098 e). Additionally, density of states analysis reveals that adsorption of NO, NO2, and O2 on the Janus ZrSSe monolayer can induce a transition from a nonmagnetic to a magnetic state. The adsorption of NO not only alters the magnetic state but also induces a transition from a semiconductor to metal, which is highly advantageous for gas sensing applications. There results suggest that the Janus ZrSSe monolayer has the potential to serve as a highly sensitive detector for NO gas.

Control of spin on structural stability, mechanical, magneto-optoelectronic and thermodynamic properties of RbTaX (X =P and As) materials: Emerging candidates for opto-spintronics and spin filter applications

In the present work, the density functional theory has been utilised in inspecting the ground state-structural, electronic, magnetic, optical, elastic and thermodynamic properties of new semiconductor RbTaX (X = P and As) half-Heuslers. Out of the possible three structures (α, β, γ) studied in ferromagnetic (FM) as well as non-magnetic (NM) phases, α – FM phase is found to be the most stable configuration. Both studied materials have estimated a net magnetic moment of 3μB, following the Slater-Pauling rule (Mtot=Ztot−8). With the use of modified Becke Johnson potential (mBJ) potential, the band profile reveals non-zero band gap in the spins and henceforth display spin filter property in the compounds. The predicted energy band gaps for RbTaP and RbTaAs are 3.04 and 2.87 eV for minority spin channels and 0.137 and 0.26 eV for majority spin channels, respectively. This unique feature of the Heusler compound may be advantageous for quantum information processing and spin-transport in electronic and magnetic devices. Also, a moderate exchange splitting and a Curie temperature well above the room temperature are noted. The stability of the materials under investigation was further confirmed by calculations of cohesive energy, formation energy, and second order elastic constants. The optoelectronic as well as thermodynamic properties of the studied compounds are also investigated. The estimated high value of refractive index (>4) is making them suitable for optical lenses. Moreover, photon energy absorption in the visible and ultraviolet spectrums renders them valuable for UV-VIS absorbers.

Structural, electronic, phonon, and elastic properties of zigzag single-walled and double-walled boron nitride nanotubes

The study used Density Functional Theory to simulate the properties of single-walled and double-walled boron nitride nanotubes. The cohesive energy calculations suggest that double-walled nanotubes are more stable than single-walled nanotubes. Double-walled nanotubes have a narrower bandgap than single-walled nanotubes. The smaller diameter of the nanotubes reduces available energy for vibrational modes. Double-walled nanotubes have larger Young’s modulus, shear modulus, and bulk modulus than single-walled nanotubes. Both single-walled and double-walled nanotubes perform like auxetic materials in some directions. The group velocity of acoustic phonons in SWBNNTs (6, 0) is higher than in SWBNNTs (12, 0).

Graphsene as a novel porous two-dimensional carbon material for enhanced oxygen reduction electrocatalysis

Graphene allotropes with varied carbon configurations have attracted significant attention for their unique properties and chemical activities. This study introduces a novel two-dimensional carbon-based material, termed Graphsene (GrS), through theoretical study. Comprising tetra-, penta-, and dodeca-carbon rings, GrS’s cohesive energy calculations demonstrate its superior structural stability over existing graphene allotropes, including graphyne and graphdiyne families. Phonon dispersion analysis confirms GrS’s dynamic stability and its relatively low thermal conductivity. All calculated GrS elastic constants meet the Born criteria, ensuring mechanical stability. Ab-initio molecular dynamic simulations show GrS maintains its structure at 300 K. HSE06 calculations reveal a narrow electronic bandgap of 20 meV, with the electronic band structure featuring a highly anisotropic Dirac-like cone due to its intrinsic structural anisotropy along armchair and zigzag directions. Notably, GrS is predicted to offer exceptional catalytic performance for the oxygen reduction reaction, favoring the four-electron reduction pathway with high selectivity under both acidic and alkaline conditions. This discovery opens promising avenues for developing metal-free catalyst materials in clean energy production.

Exploring the structural, mechanical, magneto-electronic and thermophysical properties of f electron based XNpO3 perovskites (X = Na, Cs, Ca, Ra).

Here, we present systematic investigation of the structural and mechanical stability, electronic profile and thermophysical properties of f-electron based XNPO3 (X = Na, Cs, Ca, Ra) perovskites by first principles calculations. The structural optimization, tolerance factor criteria depicts the cubic structural stability of these alloys. Further, the stability of these materials is also determined by the cohesive and formation energy calculations along with mechanical stability criteria. The electronic structure is explored by calculating band structure and density of states which reveal the well-known half-metallic nature of the materials. Further, we have calculated different thermodynamic parameters including specific heat capacity, thermal expansion, Gruneisen parameter and their variation with temperature and pressure. The thermoelectric effectiveness of these materials is predicted in terms of Seebeck coefficient, electrical conductivity and power factor. All-inclusive we can say that calculated properties of these half-metallic materials extend their route in spintronics, thermoelectric and radioisotope generators device applications.

The Stability Prediction and Epitaxial Growth of Boron Nitride Nanodots on Different Substrates.

Boron nitride (BN) is a wide-bandgap material for various applications in modern nanotechnologies. In the technology of material science, computational calculations are prerequisites for experimental works, enabling precise property prediction and guidance. First-principles methods such as density functional theory (DFT) are capable of capturing the accurate physical properties of materials. However, they are limited to very small nanoparticle sizes (<2 nm in diameter) due to their computational costs. In this study, we present, for the first time, an important computational approach to DFT calculations for BN materials deposited on different substrates. In particular, we predict the total energy and cohesive energy of a variety of face-centered cubic (FCC) and hexagonal close-packed (HCP) boron nitrides on different substrates (Ni, MoS2, and Al2O3). Hexagonal boron nitride (h-BN) is the most stable phase according to our DFT calculation of cohesive energy. Moreover, an experimental validation equipped with a molecular beam epitaxy system for the epitaxial growth of h-BN nanodots on Ni and MoS2 substrates is proposed to confirm the results of the DFT calculations in this report.

Probing the structural and electronic properties of MAX phases and their corresponding MXenes using first-principles calculations

Abstract This study delves into the theoretical exploration of the structural and electronic characteristics of 2D monolayer MXenes (M n + 1X n ) by the elimination of Al layers from their corresponding MAX-phases, M n + 1AX n (n = 1–3), through meticulous first-principles calculations. The study encompasses structural optimization and the determination of key ground state properties, including equilibrium lattice constants, energy (E 0), and volume (V 0) of both MXenes and their corresponding MAX phases. Consequently, we investigated the comparative study of the electronic properties of M n + 1AlC n (M = Ti, V, or Cr) (n = 1–3) and their MXenes for the first time by calculating the Bader charge analysis (MAX phase only) and the density of states (DOS). The analysis extends to the density of states and Bader charge assessments, facilitating a comprehensive comparison. Remarkably, the MXene monolayer showcases an elevated density of states at the Fermi level compared to its MAX phase counterpart. This disparity stems from the redistribution of 3d electrons near the Fermi level following the removal of Al layers, consequently enhancing electronic conductivity. Cohesive energy and formation energy calculations affirm the structural stability of these compounds. Furthermore, our computed values are meticulously cross-referenced with existing experimental and theoretical data, stimulating the reliability and significance of our findings.

Influence of Mg Doping on the Structure and Mechanical Properties of Al2Cu Precipitated Phase by First-Principles Calculations.

Al-Cu-Mg high-strength alloys are widely used in industrial production because of their excellent mechanical performance and good machining properties. In this study, first-principles calculations based on density functional theory were carried out to investigate the influence of Mg doping on the structural stability and mechanical properties of the Al2Cu (θ) precipitated phase in Al-Cu-Mg alloys. The results show that the structural stability, electronic structure, bulk modulus, mechanical anisotropy, and thermodynamic properties of the precipitated Al2CuMgX phase change with the concentration of Mg doping (X = 2, 4, 6, and 8). The cohesive energy calculation and electronic structure analysis show that Al2CuMg6 has a high structural stability. The criterion based on elastic constants indicates that Al2CuMg2, Al2CuMg4, and Al2CuMg8 have a brittle tendency and show strong anisotropy of mechanical properties, while Al2CuMg6 shows better comprehensive mechanical properties. The thermodynamic analysis results based on the quasi-harmonic Debye model show that the Al2CuMg6 precipitated phase has good stability at high temperatures and pressure.

An Ab-initio study on spin gapless semiconducting in novel quaternary heusler alloys RhCoVZ (Z = Al, Ga, and In): Insights into stability, electronic, magnetic, thermoelectric, and optical properties

The stability and half-metallic ferromagnetic properties of recently developed gapless semiconductor alloys, RhCoVZ (Z = Al, Ga, and In), were the subject of investigation in this research study. Three different non-equivalent structural configurations, namely type I, type II, and type III structures, have been examined. Among these compounds, Type I is characterized as the most stable phase in the ferromagnetic order, as opposed to the non-magnetic order. Through calculations of cohesive energies, formation energies, phonon dispersion curves, and elastic constants, we have demonstrated that RhCoVZ (Z = Al, Ga, and In) exhibits thermodynamic stability, as well as dynamic and mechanical. Using modified Becke-Johnson (mBJ) calculations, it has been revealed that RhCoVZ (Z = Al, Ga, and In) are spin gapless semiconductor half-metallic ferromagnets with an indirect bandgap. Additionally, it was observed that the electrons at the Fermi level (EF) are entirely spin-polarized. The total magnetic moment in all three compounds was determined to be an integer value of 2.00 µB per formula, in accordance with the Slater-Pauling rule (Mt = Zt - 24). All the calculations in this study were performed using density functional theory (DFT) based on the full-potential linearized augmented plane wave (FP-LAPW) method, which was implemented in the WIEN2k code. The effective mass of electrons/holes is (0.167/0.385) for RhCoVAl, (0.454/0.322) for RhCoVGa, and (0.604/0.242) for RhCoVIn. The thermoelectric properties of the three compounds were explored using the semi-classical Boltzmann transport theory. It was discovered that all three compounds exhibit high power factors and high Seebeck coefficients, with values reaching up to 1.5 mV/K for RhCoVAl and 1.25 mV/K for RhCoVGa. Based on the results, the highest observed ZT values for RhCoVZ (Z = Al, Ga, and In) are 0.95, 0.97, and 0.93, respectively. The study's findings indicate that these compounds possess stable characteristics, making them promising candidates for various device applications in fields like spintronics, thermoelectricity, shape memory, and spin filters. Furthermore, the investigation of their optical properties, including the dielectric function and absorption coefficient, suggests potential implications for optoelectronic applications. Overall, these materials exhibit diverse and valuable properties, opening up exciting opportunities for future technological advancements in multiple domains.

First-principles calculations to investigate structural and electronic properties of novel halides ZrIX (X = Cl, Br) for photovoltaic application

In order to meet the increasing need for proficient photovoltaic materials, the electronic, structural, optical, and photovoltaic performance of ZrX2 (X = Cl, Br, I) and ZrIX (X = Cl, Br) monolayers have been examined by extensive Density Functional Theory (DFT) based calculation. The energetic, dynamic, and thermal stability of ZrIX (X = Cl, Br) monolayers have been verified by cohesive energy, phonon spectra, and molecular dynamics calculations respectively. Under the equilibrium state, the electronic properties show that ZrICl and ZrIBr monolayers exhibit semiconductor behavior with an indirect bandgap of 1.46 eV and 1.32 eV, respectively with HSE06 functional. The impact of strain on electronic and optical properties is also calculated. To check the optical performance of the ZrIX (X = Cl, Br) monolayer, its dielectric function, absorption coefficient, reflectivity, Transmittance, conductivity, and refractive index have been obtained. The absorption coefficient indicates that ZrIX (X = Cl, Br) monolayers have starting absorption in the visible region and utmost absorption in the UV region. This indicates that ZrIX (X = Cl, Br) monolayers have potential for optoelectronic and photovoltaic applications. The solar parameters have been computed using Shockley-Queisser's method. In addition, the calculated solar power conversion efficiency of 15.91 % for ZrICl and 14.13 % for ZrIBr monolayer indicates its light absorber capacity in the solar energy harvesting domain.

The thermoelectric properties of novel two-dimensional semiconductor ZrNBr alloyed with Fluorine: A DFT+U survey

In this survey, the thermoelectric properties of novel two-dimensional transition metal halide (ZrNBr) alloyed with Fluorine (F) in the replacement of Br atoms (with x = 0.5) have been studied. The density functional theory along with Hubbard’s potential has been used to study the density of states, the Seebeck coefficient, electrical conductivity, the electronic contribution of thermal conductivity, and the thermoelectric power factor. The dynamic and structural stability of the compounds has been proven by cohesive energy and phonon calculation results. By considering Hubbard’s potential of 3 eV the energy band gap of the electronic density of states has been enlarged to values of 2.73, and 2.7 eV for pure ZrNBr, and ZrNBr0.5F0.5, respectively. Moreover, the largest values of the thermoelectric power factor at room temperature (300 K) and without considering Hubbard’s potential were 29.12 × 1016 and 101 × 1016μW/m K2 s and at the negative chemical potential for pure ZrNBr, and ZrNBr0.5F0.5, respectively. While considering Hubbard’s potential, the largest peaks at 300 K were 26.42 × 1016μW/m K2 s (at positive chemical potential) and 41.41 × 1016μW/m K2 s (at negative chemical potential), for pure ZrNBr, and ZrNBr0.5F0.5, respectively. These values are in the ranges of the results for materials which are potential candidates for thermoelectric applications.

Investigation on prospective thermoelectrics — cubic Nd-doped LMO and rhombohedral Cu4Mn2Te4 materials — first principles approach

Structural, electronic, magnetic and optical properties of Cu4Mn2Te4 have been reported earlier by the authors, and here, the transport properties of the same are discussed along with the band structure investigation of the neodymium-doped cubic material LMO (LiMn2O4), namely LiMn[Formula: see text]Nd[Formula: see text]O4 compound, under spin polarized schemes through the First Principles calculations. The Full Potential-Linearized Augumented Plane Wave Method (FP-LAPW) method is adopted to investigate the electronic structures based on the framework of Density Functional Theory (DFT). Exchange potentials are treated using the Generalized Gradient Approximations (GGA). Cohesive energy calculations reveal that the ferromagnetic phase of LiMn[Formula: see text]Nd[Formula: see text]O4 and the antiferromagnetic phase of Cu4Mn2Te4 exhibits a stable phase. Of these, FM-LiMn[Formula: see text]Nd[Formula: see text]O4 shows a semi-metallic-like behavior in spin-up channel and metallic behavior in spin-down channel whereas antiferromagnetic Cu4Mn2Te4 exhibits a band gap in both spin-up and spin-down channels. Dirac points are identified at −0.0625[Formula: see text]eV in the band structure plot of FM-LiMn[Formula: see text]Nd[Formula: see text]O4 at its high symmetry points [Formula: see text] and W which is an indication of high electron mobility at ambient condition. The presence of flat and dispersive bands around the Fermi energy level is an indication of high thermopower, and it is present in both the compounds FM-LiMn[Formula: see text]Nd[Formula: see text]O4 and AFM-Cu4Mn2Te4. From the present computations, at 300[Formula: see text]K, a power factor range of ([Formula: see text] scaled by relaxation time in [Formula: see text]W/msK2) [Formula: see text] and [Formula: see text] is obtained for ferromagnetic LiMn[Formula: see text]Nd[Formula: see text]O4 compounds at up and down spins, respectively. A typical power factor ([Formula: see text]Wm[Formula: see text]s[Formula: see text]K[Formula: see text]) of [Formula: see text] and [Formula: see text] is obtained for antiferromagnetic Cu4Mn2Te4 at 325[Formula: see text]K required for good thermoelectric performance.

Three‐Dimensional Porous Diboron Dinitride as a High‐Performance Anode Material for Sodium/Potassium‐Ion Batteries: A First Principles Study

Abstract2D boron nitride shows great promise in the photoelectric device, deep UV emitter and field effect transistor with good thermal stability, high mechanical robustness and chemical inertness; nonetheless, its inherently low electrical conductivity and small pore size have severely hindered the electrochemical kinetics and lead to a poor rate capability. Herein, we design a novel porous 3D−B2N2 structure by assembling the orthorhombic B2N2 monolayer into t‐C24 lattice and assesse its feasibility as the anode material of sodium(SIBs)/potassium(PIBs) ion batteries. The ab initio molecular dynamics (AIMD) simulation, Born‐Huang criteria, phonon spectrum and cohesive energy calculations confirms that the resulting 3D−B2N2 possesses excellent mechanical, thermal and dynamical stability. Different from the pristine h‐B2N2, an improved electrical conductivity is observed for 3D−B2N2 with a small band gap of 0.66 eV. Moreover, the low mass density, unique porous structure and strong adsorption energy make the 3D−B2N2 an outstanding electrode material for SIBs/PIBs with high storage capacities of 599.90 (479.92) mA h/g, low averaged open circuit voltages of 0.13 (0.27) V, low diffusion barriers of 0.04 (0.008) eV, and small volume expansions of 0.96 % (2.63 %). All the encouraging findings reveal that the 3D−B2N2 anode deserves further experimental investigation for SIBs/PIBs.

Impact of Strain on Electronic and Optical Properties of MgClBr Monolayer: First-principle Calculation

We have introduced a novel halide monolayer, MgClBr, and performed a comprehensive analysis of its structural, and optoelectronics properties using first-principles calculations. The electronic band structure revealed that MgClBr material has a wide “Γ-Γ” direct band gap. The monolayer's dynamic, thermal, and energetic stability is verified through phonon spectra, AIMD calculation, and cohesive energy calculation, respectively. The MgClBr exhibited a 6.08 eV band gap from HSE06 hybrid functional, slightly larger than MgBr2 but smaller than MgCl2 monolayers. The Strain effects on the optoelectronic characteristics are examined. The MgClBr monolayer shows a band gap of 4.23 eV for −10% and 4.30 eV for + 10% strain, remaining stable under these conditions. Notably, the MgClBr monolayer has favourable band-edge alignment for oxidation–reduction processes involved in water splitting at pH zero. Additionally, the monolayer exhibited significant absorption in extreme UV regions, suggesting its potential as a material for optoelectronic nanodevices like UV-emitters and detectors, electrically insulators and non-reflective overlay material.

Unraveling the structural and mechanical stability, electronic, and optical properties of (LaxSr1-xVO3)n (n =1, 2; x = 0, 0.5, 1)

We have investigated the structural, chemical, and mechanical stabilities, electronic structures, and optical characteristics of (LaxSr1-xVO3)n ( where, n =1,2; x = 0, 0.5, 1) systems using the ab-initio calculations. The negative values obtained from formation and cohesive energy calculations, modulus of elasticities, Poisson’s and Pugh’s ratios, anisotropy factor, and Cauchy pressure indicate that these materials have excellent structural and mechanical stability, which can be synthesized experimentally. Furthermore, the Mott-Hubbard metal-insulator transition (MIT) is investigated using the maximum entropy model (MEM) from the data obtained from dynamical mean field theory (DMFT). From the calculation, MIT are observed for pristine LaVO3 and SrVO3 at U = 4.5 eV with β = 8.0 (eV )−1 and U = 2.5 eV with β = 6.0 (eV )−1, and the MIT parameters for LaSrV2O6 system are observed at U = 4.0 eV with β = 10.0 (eV )−1 respectively. The photo-induced behaviors of these materials have also been investigated using the dielectric function, index of refraction, Eloss function, absorptivity, and optical conductivity in the IR-to-UV regions, including the visible spectrum.

Visible light response in 2D QBi (Q=Si, Ge and Sn) monolayer semiconductors: A DFT based study

In this work, two dimensional QBi (Q=Si, Ge and Sn) monolayers with P6m2 space group are investigated by using first principle calculations based on the density functional theory. As the first step, the stability of the proposed monolayer materials was examined. Based on our calculations, QBi (Q=Si, Ge and Sn) monolayer structures have proper structural and dynamic stabilities, so they are promising substances to fabricate experimentally. Investigate of electronic structures which confirmed by cohesive energy calculation and phonon dispersion simulation respectively. Evaluating the electronic properties of these materials shows that they are semiconductors with small direct band gaps which can be effectively adjusted by applying compressive and tensile strains. Moreover, based on our optical properties evaluation these monolayer materials show strain tunable optical characteristics in visible region of light. The results of this research reveal that QBi (Q=Si, Ge and Sn) monolayers are promising materials for using in different electro-optical devices especially electromechanical and optical sensors.