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The structural, optoelectronic, and transport features of novel X 3 MgNa (X = Cl, Br, and I) antiperovskites compounds are revealed by using the density functional theory. The structural stability of all of the compounds under consideration has been verified by using the Birch-Murnaghan equations of states, which indicate that all compounds have structural stability due to ground-state energy levels being negative. The electronic band structure and TDOS results reveal that the electronic band gap of Cl 3 MgNa is 4.22 eV, Br 3 MgNa is 2.18 eV, and I 3 MgNa is zero eV. The partial density of state PDOS results demonstrate that the formation of the conduction and valence bands is due to the hybridization of Cl- 3p , Br- 4p , Na-3p, and I- 5p states. In terms of optical results, reverse perovskite with Br as a cation has shown much better optical conductivity in the ultraviolet range. Therefore, Br 3 MgNa is a potential candidate among all the compounds for optoelectronic-based applications. The Boltztrap code, which is patched with WEIN2K code, has been used to compute the thermoelectric characteristics of the examined compounds. Br 3 MgNa has a greater power factor, a high electrical conductivity, and a figure-of-merit; ZT approaches unity, indicating a promising option for thermoelectric applications. • X 3 MgNa (X = Cl, Br, and I) antiperovskites compounds were studied by FPLAPW method for photovoltaic and thermoelectric properties. • To analyze the structural,dynamical stability and thermodynamic stability by tolerance factor, phonon dispersion, cohesive energy, and enthalpy of formation. • High absorption coefficients in the ultraviolet (UV) range and low reflectivity are highly valuable for optoelectronic applications. • The Br 3 MgNa is the best material due to its high figure of merit and power factor. [ABSTRACT FROM AUTHOR]

Using first-principle calculations, we have studied the structural and electronic properties of the Gallium Phosphide (GaP) nanoribbon doped with rare earth (RE) metal elements. The substitution of Ga and P atoms with RE leads to the structural deformation in zigzag GaP nanoribbon. For every nanostructure under study, the binding energy (E b), density of states (DOS), and electronic band structures have been computed. The bare and pristine undoped GaP show non-magnetic behavior. The bare z-GaPNR shows metallic nature while the pristine z-GaPNR exhibits band gap of 2.44 eV with indirect characteristics. With Samarium (Sm) and Gadolinium (Gd) doping in z-GaPNR, a transformation of the semiconducting nature of z-GaPNRs turns to half metallic one. The transport properties show that half-metal ferromagnetic behavior with 92%–98% spin polarization at the Fermi level is produced by RE (Gd, Sm) co-doped z-GaPNRs. The synergistic effect of the Gd and Sm impurities are seen to diminish energy band gaps. Conversely, we have the energy band gap in spin down energy levels results in semiconducting behavior, whereas in the spin up energy state, metallic behavior is observed. This could be caused by the 4 f -states of the Sm and Gd dopants. Therefore, this work presents half-metallic (HM) properties for RE-doped z-GaPNRs. Our study depicts that the electrical, spin, and transport properties of z-GaPNRs could be altered magnificently by co-doping of Gd and Sm rare earth metals. Additionally, the current findings can be used to create a workable method of absolute fermi level shifting for spin energy levels, which is required for applications involving spintronic devices, spin filters, as well as for z-GaPNRs' electrical characteristics modifications. • The impact of double RE (Gd, Sm) co-doped z-GaPNRs on their magnetic properties. • RE co-doping results in half-metallic behavior with 92%–98% spin polarization. • RE (Gd, Sm) co-doping in z-GaPNRs reduces energy band gaps. • There is finite energy band gap in spin down and metallic behavior in spin up states. [ABSTRACT FROM AUTHOR]

In this study, we introduce a novel two-dimensional (2D) monolayer of CrSiM 2 N (M = As, P and N Se, Te) and explore its electronic properties. For the first time, we employ density functional theory and investigate the electronic and thermoelectric (TE) properties of CrSiM 2 N (M = As, P and N Se, Te) monolayers. Our calculated phonon band structure confirms that these monolayers are stable and can potentially be synthesized experimentally. The CrSiM 2 N (M = As, P and N Se, Te) monolayers exhibit an indirect band nature, with the CBM and VBM located at the K and G-points of the first Brillouin zone, respectively. We have also calculated the thermoelectric properties of these systems, which suggest that these monolayers could play a crucial role in enhancing the thermoelectric performance. Furthermore, we investigated the electronic, optical and thermoelectric properties of CrSiM 2 N (M = As, P and N Se, Te) and MoTe 2 van der Waals heterostructures (vdWHs). The electronic band structure exhibits an indirect semiconductor nature, with the conduction band maxima and valence band minima originating from the CrSiM 2 N (M = As, P and N Se, Te) and MoTe 2 monolayers, thereby confirming a type II band alignment. The optical properties indicate that these vdWHs can absorb a broad range of light, from the ultraviolet to the visible and infrared regions. We demonstrated that CrSiM 2 N (M = As, P and N Se, Te) monolayers exhibit p-type TE behavior, while their vdWHs counterparts exhibit n-type TE behavior. • Novel two-dimensional (2D) CrSiM 2 N (M = As, P and N Se, Te) monolayers. • We construct ultrathin vdWH by vdW stacking of CrSiM 2 N (M = As, P and N Se, Te) monolayer and MoTe 2 monolayers. • Type-I and type-II band alignments. • Thermoelectric properties of CrSiM 2 N (M = As, P and N Se, Te) and MoTe 2 monolayers. • CrSiM 2 N (M = As, P and N Se, Te) monolayers exhibit p-type TE behavior, while their vdWHs counterparts exhibit n-type TE behavior. [ABSTRACT FROM AUTHOR]

In this work the electronic and optical properties of luminescent materials XSiN 2 (X = Ca, Sr, Ba) were revisited based on density function theory (DFT) calculations with a newly developed DFT-1/2 scheme. It was found that the DFT-1/2 correction on nitrogen can well correct the band gaps to approach the experimental values, showing its advantage comparing to the Perdew–Burke–Ernzerhof (PBE) and the Strongly Constrained and Appropriately Normed (SCAN) functionals. Then the electronic band structures and optical properties of the three compounds were investigated using the DFT-1/2 scheme. Within the three compounds, the band gap shows a monotonic decrease along with the atomic number of alkali earth metal mainly due to the downshift of the conduction band edge, where the electronic conductivity is primarily based on electron since it shows a much smaller effective mass than hole. CaSiN 2 owns more flat valence bands, while SrSiN 2 gives lighter electron. Moreover, the three compounds show high optical absorption, but distinct behavior of light absorption and refractivity in specific energy range, suggesting their applications in optical applications. • A more accurate method was chosen to address the band gap of XSiN 2 (X=Ca,Sr,Ba). • The physical properties were computationally investigated using this approach. • The compounds are predicted to be good candidates for luminescent application. [ABSTRACT FROM AUTHOR]

The major goal of the research described in this paper is to investigate the structure of electronic band and band gap of the novel semiconductor lead (II) trioxovanadate (V) chloride (PbVO 3 Cl). Depending on both experimental and theoretical (computational) results, the utility of PbVO 3 Cl as a semiconductor in solar fuel devices was discussed. The optical band gap was determined experimentally by applying Tauc Plot method to the absorption spectra of PbVO 3 Cl. Additionally, computational approaches for the structure prediction of PbVO 3 Cl have been studied. The electronic band structures were examined theoretically using local density (LDA), generalized gradient (GGA), and hybrid (HSE06) approximations. PbVO 3 Cl, which has an optical band gap of about 2.2 eV, has been shown to have promising photocatalytic properties. As a result of these approximations, the transition type of PbVO 3 Cl was determined as indirect. We also discussed the potential future application of PbVO 3 Cl in Lewis solar fuel devices as a combination of the photoanode and Si photocathode. And the solar efficiency of the PbVO 3 Cl–Si double-layer semiconductor system was calculated. Further experimental proofs can be important. • PbVO 3 Cl. • Semiconductor. • Band gap. • Theoretical efficiency. [ABSTRACT FROM AUTHOR]

We investigate the optical and electronic characteristics of parental MnNiGe and doped MnNi 1-x Ag x Ge (x = 4 %, 8 %, and 12 %) for photodetector and other electronic applications. First principles are applied to every calculation performed in the context of DFT. The generalized gradient approximation with the Hubbard potential included (GGA + U) has been chosen as the appropriate approximation to handle systems with strongly coupled electrons. The semi-metallic parental MnNiGe and doped MnNi1 -x Ag x Ge (x = 4 %, 8 %, and 12 %) is ideal for conducting materials in electronics due to band overlapping, according to our findings. Degenerate doping of Ag into MnNiGe includes spinning the Fermi level, changing the DOS profile, and reducing the density of Fermi level states that allow tunneling from the valence band to the conduction band. An important part of this research is analyzing the refractive index, reflectivity, extinction coefficient, dielectric function, absorption coefficient, and energy loss function of parental MnNiGe and doped MnNi 1-x Ag x Ge (x = 4 %, 8 %, and 12 %). According to our findings, it is possible to create a photo detector based on MnNi 1-x Ag x Ge (x = 4 %, 8 %, and 12 %) that can detect light in the visible range (below 500 nm). It has also been found that the MnNi 1-x Ag x Ge (x = 4 %, 8 %, and 12 %) exhibits the highest sensitivity to light with a wavelength of 450 nm. Due to its advantageous optical characteristics in the visible and ultraviolet regions, this material could be useful for the development of numerous optoelectronic applications. • The study applies first principles and DFT with GGA + U approximation to investigate the structural and optoelectronic properties of MnNi1-xAgxGe alloys with Ag doping concentrations of 4 %, 8 %, and 12 %, highlighting potential applications in photodetectors and other electronic devices. • It presents a detailed analysis of the impact of non-magnetic silver doping at the nickel site, showing a transition to semi-metallic behavior and modifications in electronic band structure, resulting in no band gap and a potential increase in conductivity and optoelectronic functionality. • The research concludes that doped MnNi1-xAgxGe alloys exhibit enhanced optical properties, such as a higher sensitivity to visible light, particularly at 450 nm, making them suitable for the development of new optoelectronic devices. [ABSTRACT FROM AUTHOR]

The demand for sustainable semiconducting devices that can be used in various applications necessitates the development of revolutionary materials with multifunctional properties. Using van der Waals interactions corrected first-principles density functional theory (DFT) calculations, we propose porous g-XO (X = Ge, Cu) inorganic graphenylene monolayers. These monolayers extend the family of synthesized porous organic graphenylene materials. Stability checks reveal that the g-XO monolayers are energetically, mechanically, dynamically, and thermally stable. Additionally, g-GeO monolayer is auxetic 2D material. The auxetic property of g-GeO monolayer could be advantageous for important applications in mechanics and tissue engineering, electromechanical devices, and flexible electronics. Based on the HSE06 electronic band structure results, these g-CuO and g-GeO monolayers exhibit wide and ultra-wide indirect bandgap semiconducting properties, respectively. The satisfactory absorption coefficient of 10 4 –10 5 cm−1 spanning the visible to UV region implies their potential for optoelectronics and UV shields applications. Our theoretical results provide a hints for the potential of these porous g-XO monolayers in energy harvesting/conversion, nanofiltration membranes, optoelectronic, thermoelectric, and flexible electronics. [Display omitted] • The porous g-XO (X = Ge, Cu) monolayers have been investigated using DFT calculations. • g-XO monolayers are energetically, mechanically, dynamically, and thermally stable. • g-GeO monolayer is auxetic 2D material. [ABSTRACT FROM AUTHOR]

Transition metal nitrides are ceramic materials known for their remarkable physical and mechanical characteristics, particularly their hardness. As part of this study, the structural, mechanical, electronic, phonon, and optical properties of nitrides were investigated. We focused on TiN in the NaCl–B1 and ZB-B3 phases and VN in the ZB-B3 using the density functional theory approach. The results show that the TiN equilibrium lattice constant in the NaCl–B1 phase is very close to what has already been reported. This confirms the overall reliability of the different phases. Furthermore, the heat of formation data suggests that TiN in both the NaCl–B1 and ZB-B3 phases is thermodynamically stable. The elastic constants confirm the mechanical stability of TiN in the NaCl–B1, ZB-B3, and VN in ZB phases. The bulk-to-shear ratio highlights that TiN in the NaCl–B1 phase exhibits brittleness, whereas TiN in the ZB-B3 phase displays ductility. Electronic band structure and total density of states calculations for both TiN in NaCl–B1 and ZB-B3 phases demonstrate their conductivity due to a pronounced valence-conduction overlap around the Fermi energy level. The low number of electrons accumulated at the Fermi energy level in the density of states (DOS) indicates electronic stability for TiN in the NaCl–B1 and ZB-B3 phases. The electron charge density plots indicate the presence of electrovalent (ionic) bonds between Ti-3d, V-3d, and N-2p. Additionally, the phonon dispersion curves reveal dynamical stability in both phases. Regarding optical properties in TiN, our predictions establish a distinct correlation between the loss function, reflectivity, and absorbance spectra within the 12.5 nm–25 nm energy range, with TiN in the NaCl phase exhibiting dominance. Notably, the NaCl phase exhibits higher absorption compared to the ZB phase, making it a promising candidate for use as a photocatalyst. Furthermore, the imaginary conductivity spectra align with the electronic properties, collectively indicating that these materials possess conductive characteristics. • TiN in NaCl–B1 and ZB-B3 phases were investigated as possible candidates as solar absorbers.. • The NiCl–B1 and ZB-B3 phases are Structural, mechanical, electronic, and dynamically stable. • Loss function, absorption and reflectivity spectra show relatively good correlation at 55 eV in TiN phases. • High hardness (H V) is predicted for TiN in NaCl–B1 and zinc-blende phases. • Our results should assist in identifying potential materials for the above applications respectively. [ABSTRACT FROM AUTHOR]

In this study, electronic properties of graphene nanoribbons with armchair edges (AGNRs) have been investigated with Density Functional Theory (DFT). Effects of heavy metal (HM) elements, including Zinc (Zn), Cadmium (Cd) and Mercury (Hg) atoms on electronic behavior of AGNRs have been calculated by passivating for both one and two edges of AGNRs in detail. To explain the electronic behavior of investigated AGNRs, the electronic band structure, the density of states (DOS), total energy have been calculated. Energetically favorable structures have been determined using calculated binding energy values. The obtained bandgap values of investigated structures changes between 0.30 and 0.64 eV. Increasing atomic number of passivation atoms have led to an increment in the bandgap of AGNRs. • Ab initio calculations of armchair graphene nanoribbons are carried out. • Electronic properties of graphene nanoribbons with heavy metals are investigated. • Electronic band gap values of graphene nanoribbons are calculated. • Energetically structures are determined. [ABSTRACT FROM AUTHOR]

By using of the first-principles calculations based on density functional theory, a novel monolayer planar structure named C 64 -graphyne is predicted. Tetratomic and hexatomic rings, as well as C C triple bonds exist in this new stable structure with the lattice parameter of 9.291 Å. The carbon hexatomic ring in C 64 -graphyne contains two quite distinct C C bonds, which is known as cyclohexatriene. Its electronic band structures show a semiconductor nature with a narrow direct band gap of 0.35 eV. Interestingly, by substituting a carbon atom with one nitrogen atom either in the hexatomic ring or in the chain of C 64 -graphyne, two stable planar structures are obtained. Such doping with nitrogen atom induced metallic properties in this monolayer structure. Further investigation shows that the alternating substitution of boron and nitrogen atoms for all carbon atoms in C 64 -graphyne also induced a new stable structure, the (BN) 64 structure. The electronic studies proved its insulator property with the band gap of 4.08 eV. • The cyclohexatriene exist in C 64 -graphyne. • Tetratomic, hexatomic rings exist in C 64 and BN 64. • C 64 is a semiconductor, BN 64 a insulator. [ABSTRACT FROM AUTHOR]

Motivated by current interest in the materials with heavy elements, we perform theoretical calculations on two 5 d -electron compounds, Sr M 2 Ge 2 (M = Ir, Pt), which are observed superconductivity by former experiments. The electronic and phonon properties are obtained by ab initio calculations. The results show that the Pt/Ir-5 d orbital are strongly hybridized with Ge-4 p orbital, which contribute mainly to electronic states near the Fermi level (E F). Two (four) bands in SrIr 2 Ge 2 (SrPt 2 Ge 2) cross E F to construct rather three-dimensional Fermi surfaces. In SrPt 2 Ge 2 , novel Dirac cones around Σ point are observed, which are related to the band inversion between Ge-4 p and Pt-5 d orbital. When spin-orbit coupling (SOC) is considered, the Dirac cone along Z-Σ becomes fully gapped, but the cone along Γ − Σ line is stable. The lattice dynamics and electron-phonon coupling (EPC) are also studied with and without SOC. We find EPC is quite weak in SrIr 2 Ge 2 but strong in SrPt 2 Ge 2. Unstable phonon modes are observed in SrPt 2 Ge 2 with ThCr 2 Si 2 -type structure, corresponding to metastable phase observed by experiments. • The electronic structure and lattice dynamics of two 5d -electron potential superconductors SrIr 2 Ge 2 and SrPt 2 Ge 2 are investigated. • In SrPt 2 Ge 2 , novel Dirac cones are around Σ point, caused by the band inversion between Ge- 4p and Pt- 5d orbital. • It is found that the electron-phonon coupling (EPC) is quite weak in SrIr 2 Ge 2 but strong in SrPt 2 Ge 2. [ABSTRACT FROM AUTHOR]

Abstract Bulk Ge-Sn chemical compounds have rarely been synthesized at ambient pressure, due to the low solubility of Sn in Ge. Atomic and electronic structures can be significantly changed by pressure, which holds the promise to synthesize bulk Sn-Ge compounds. Here, we identify the formation of three stoichiometric Ge-Sn compounds (Ge 2 Sn, Ge 3 Sn 2 and Ge 2 Sn 3) under high pressure, using the CALYPSO structure prediction method in combination with first-principles calculations. The concentration of Sn (60%) in Ge 2 Sn 3 is higher than that of any synthesized Ge-Sn known compounds. With an increasing Sn concentration, the Ge Ge bonding patterns of Ge-Sn compounds evolve from infinite 2D-nets (Ge 2 Sn) in turn to rings (Ge 3 Sn 2) and then tetramers (Ge 2 Sn 3). The calculated electronic band structures show that all the predicted phases are metallic. Our results will pave way for further understanding of the Ge-Sn phase diagram. Highlights • The concentration of Sn in proposed Ge 2 Sn 3 is higher than that of any synthesized Ge-Sn known compounds. • Unlike the earlier work, the proposed Ge-Sn compounds are all metallic. • With the increasing Sn concentration, intriguing Ge−Ge bonding features are identified in the Ge-Sn compounds. [ABSTRACT FROM AUTHOR]

Abstract A new simple cubic perovskite superconductor (Ba 0.62 K 0.38)(Bi 0.92 Mg 0.08)O 3 with a T c mag ∼30 K has been recently synthesized by utilizing facile hydrothermal conditions at 220 °C. Here, we have employed the pseudo-potential plane-wave (PP–PW) approach based on the density functional (DFT) theory, within the generalized gradient approximation (GGA) to calculate and investigate the physical and electronic properties of this new superconductor. The calculated elastic constants satisfy the Born mechanical stability criterion. Based on the calculated data of Cauchy pressure, Pugh ratio and Poisson's ratio, the compound under investigation is found to be brittle nature. The calculated Peierls stress indicates easier movement of dislocations between glide planes. The energy bands crossing the Fermi level (E F) in electronic band structure reveal metallic behavior of the newly synthesized compound. The contribution of O-2 p orbital electrons at the E F is higher than those of other orbital electrons as seen from partial density of states. The formation of saddle point owing to the flatness of the energy band may enhance the electron pairing which subsequently leads to high- T C superconductivity. The valence electron charge density map shows the isotropic nature of charge distribution. Coexistence of electron and hole like pockets form the multi sheets Fermi surfaces and exhibit the multi-band nature of the compound. Importantly, Fermi surfaces with flat faces are considered as favorable condition for Fermi surface nesting. The calculated value of electron-phonon coupling constant (λ = 1.61) implies that the studied compound can be treated as a strongly coupled superconductor. Further, the thermodynamic properties at elevated temperature and pressure are calculated and analyzed for the first time by using quasi-harmonic model. Highlights • DFT calculations on mechanical, electronic and thermodynamic properties of (Ba 0.62 K 0.38)(Bi 0.92 Mg 0.08)O 3 material. • Elastic properties calculation reveal mechanically stable and brittle nature of compound. • Thermodynamic properties indicate promising material for thermal barrier coating (TBC). • The metallic behavior of this superconductor is confirmed by electronic band structure. • The flatness of the band near E F may enhance electron pairings which consequently reveals superior superconducting behavior. [ABSTRACT FROM AUTHOR]

An unrealistically large value of the Gruneisen parameter is required to explain the valence transition which occurs at 42 K in YbInCu4 as due to a Kondo Volume Collapse. A hint as to the origin of the transition lies in the large change in carrier density which occurs at the transition, from trivalent semimetallic behavior at high temperature to mixed valent metallic behavior at low temperature. In this paper we report measurements of the Hall coefficient RH for temperatures in the range 15-300 K for a series of RXCu4 compounds (R = Yb, Lu and X = Au, Zn, Cd, Mg, Tl) that form in the cubic C15b structure. For all X the Hall coefficients are small (∼10-10 m3/C) so that the transport appears to be metallic. The observation that low carrier density is unique to RInCu4 leads us to hypothesize that the valence transition (which is also unique to YbInCu4) is connected with the existence of a quasigap, which is a common feature of the band structure of RXCu4. The quasigap allows for two competing hybridization states of the 4f electrons: a small TK semimetallic state and a large TK metallic state. © 1998 Elsevier Science Ltd. All rights reserved.

In this research work, the structural, electronic, optical characteristics, and the work function of the asymmetric functionalized Y 2 CTT' (T, T' = F, Cl, Br) MXene monolayers have been investigated using the density functional approach. Herein, bare Y 2 C MXene monolayer is metallic which is functionalized with two different halide atoms. The upper surface of Y 2 C monolayer is terminated with T halide atom and the lower surface is terminated with T′ halide atom. For the computation of electronic band structure, generalized gradient approximation with PBE functional as well as hybrid functional (HSE06) is employed, which ensures that the Y 2 CClBr, Y 2 CFBr and Y 2 CFCl monolayers are semiconductor with the indirect bandgap of 1.66 eV, 1.81 eV and 1.82 eV. The evaluation of optical properties using the random phase approximation suggests that the Y 2 CTT' monolayers start absorption in IR region, exhibits a small absorption in the visible part and a significant absorption in ultraviolet part of the electromagnetic spectrum. Hence, Y 2 CTT' monolayers are the promising candidates in photonic devices specifically ultraviolet detectors, ultraviolet radiation absorbers, etc. [Display omitted] • The electronic and optical properties of pristine monolayers are tuned by asymmetric functionalization. • The Y 2 CClBr, Y 2 CFBr and Y 2 CFCl MXene monolayers are energetically, and dynamically and thermally stable confirmed by cohesive energy, phonon dispersion spectra, and AIMD simulation. • Electronic band structure calculations using HSE06 functional confirms that all three monolayers are indirect bandgap semiconductors. • All three monolayers are promising candidates for optoelectronic devices, such as UV absorber, UV detector, etc. [ABSTRACT FROM AUTHOR]

Beginning from the density functional theory, the linear response theory within the framework of time dependent density functional theory has been applied to study the electron energy loss spectra of ZnSe. The ground state is obtained using first-principles Full-Potential Linearized Augmented Plane Wave method. After settling the crystal structure, the electronic properties such as band structure and density of states are calculated. The electron energy loss spectra are found considering exchange-correlation kernels namely adiabatic local density approximation, long range contribution and the bootstrap. For the sake of completeness and comparison, results using random phase approximation are also incorporated. The inclusion of local field effects in all the kernels improve the agreement of optical and electron energy loss spectra with experimental data. Moreover, agreement in the plasmon peak positions, found using different kernels considering local field effects, with experimental data has also improved. • This is the first attempt to calculate the electron energy loss spectra (EELS) of ZnSe using various exchange correlation kernels within the framework of LR-TDDFT. • Effect of local field is also observed on the EELS, real and imaginary part of dielectric function. • The LFE causes blueshift in peak position of ε 2 by ∼ 0.05eV and ∼ 0.15 eV in EELS. Moreover, intensity of peaks in the studied spectra reduces after incorporating LFE. • Static dielectric constant considering LFE is in reasonable agreement with experiment. [ABSTRACT FROM AUTHOR]

In this study, we have investigated the electronic , structural, elastic, optical and thermodynamic properties of the copper-based ternary semiconductors, that is, KCuZ (Z= Te, Se). The properties of these materials have been precisely determined based on first-principle calculations. The lattice constants, bulk modulus and equilibrium total energies were obtained from Murnaghan equation of state and have a good agreement with other theoretical and experimental methods. The absorption spectra was analyzed to determine the active window of electromagnetic spectrum of the compounds. The elastic constants of these materials were elucidated and hence provided vital information about the material's ability to withstand external stress. The results indicate that the materials conform to the stability criteria with brittle behavior and anisotropic nature in the HCP structure. The electronic band structures and density of states were computed and the results obtained suggests that the these materials have a band gap of 1.25 eV and 1.1 eV for KCuTe and KCuSe respectively and therefore they are suitable for photovoltaic applications. The materials are also found to posses desirable optical properties i.e. the materials have a good optical absorption since highest absorption peaks occur within the UV region, small reflectivity and high dielectric constant indicating that the materials is suitable for use as solar absorbers. • KCuTe and KCuSe are both hexagonal in nature and belong to space group P63/mmc. • KCuTe and KCuSe structures are mechanically and thermodynamically stable. • All the two compounds are brittle. • Band gaps of 1.1 eV for KCuSe and 1.25 eV fo KCuTe. [ABSTRACT FROM AUTHOR]

Lead-free halide double perovskite materials have recently attracted considerable interest from the scientific community due to their vast potential in optoelectronic applications without toxicity issues. Herein, we report a new lead-free halide double perovskite, namely Cs 2 CdZnCl 6 , based on DFT calculations. We found that Cs 2 CdZnCl 6 is mechanically stable in the cubic nonmagnetic phase. The Electronic band structure calculations revealed that this compound exhibits a direct semiconductor band gap of 1.43 eV. The dielectric function ε , reflectivity R , refractive index n , absorption coefficient α , and optical conductivity σ are analyzed up to 13.0 eV. Furthermore, it is found that the studied compound has a significant photoresponse in the ultraviolet light region. Finally, the findings suggest that Cs 2 CdZnCl 6 is a promising material for optoelectronic applications. • A new lead-free halide-based double perovskite compound Cs 2 CdZnCl 6 has been proposed. • The crystal structure and stabilities of the considered material are completely explored. • Cs 2 CdZnCl 6 exhibits a semiconducting nature with a direct band gap of 1.43 eV. • Good optical responses in the ultraviolet light region have been observed. • Cs 2 CdZnCl 6 can be a promising material for optoelectronic devices. [ABSTRACT FROM AUTHOR]

After the discovery of graphene and its unique optical properties, the investigation and discovery of 2D materials expanded. Electrons and phonons of 2D materials react differently to light compared to their bulk state, which will cause unique optical properties. Compared to graphene, 2D monolayer MXenes have non-zero gap energy, which increases their application in optical industries. In this article the density-functional-theory (DFT) approach is employed to investigate the electronic, structural and optical properties of (M 2 CO 2 , M = Zr, Sc, Mo and Hf) 2D monolayer MXenes. On the other hand, with the addition of Hydrogen to MXenes (M 2 C(OH) 2), their structural and optical properties change significantly. The electronic band structure results showed that Zr 2 CO 2 , Sc 2 CO 2 and Hf 2 CO 2 monolayers are semiconductors with indirect band gaps and Mo 2 CO 2 is a conductor. By adding hydrogen to the layers, Sc 2 CO 2 monolayers changed from an indirect band gap semiconductor to a direct band gap semiconductor. The optical results showed that the highest static refractive index belongs to Zr 2 CO 2 monolayers and the lowest to Sc 2 CO 2. By adding hydrogen to the system, the refractive index of Sc 2 C(OH) 2 increases. According to the imaginary part of the dielectric function, the optical gap of Sc 2 CO 2 has the highest value. Also, Mo 2 CO 2 monolayers does not have an optical gap. These results are in agreement with the electronic band structure results. • Zr 2 CO 2 , Sc 2 CO 2 and Hf 2 CO 2 monolayers are semiconductors with indirect band gaps and Mo 2 CO 2 is a conductor. • Sc 2 CO 2 monolayers changed from an indirect band gap semiconductor to a direct band gap semiconductor. • The highest static refractive index belongs to Zr 2 CO 2 monolayers. • Mo 2 CO 2 monolayers does not have an optical gap. • By adding hydrogen to the system, the refractive index of Sc 2 C(OH) 2 increases. [ABSTRACT FROM AUTHOR]

We report in the present paper ab initio calculations of the structural, electronic and optical properties of zinc blende quaternary alloys Cd x Mg (1-x) Te y S (1-y) lattice matched to CdX (X = S, Te) exploring the density functional method within the generalized gradient approximation (GGA). From the obtained values of the ground state energy, we have determined the structural parameters and the band gap energies. We found an underestimation of the gap energies obtained for both (GGA-PBE) and the Modified Becke-Johnson exchange potential (TB-mbJ) approximations for the CdS, CdTe, MgS, and MgTe. Even though mbJ significantly corrects the energy gaps, it is no longer valid to properly reproduce the exchange-correlation potential. Consequently, we tend to use the corrective term Δ E to exploit it to enhance the electronic band structures. Moreover, we have reported the concentration depending on the refractive index and the dielectric function using (mbJ). The critical thickness, for which the lattice of the Cd x Mg (1-x) Te y S (1-y) matches CdS and CdTe, respectively, are determined. The results show that for all Cd and Te incorporated amounts, the Cd x Mg (1-x) Te y S (1-y) lattice matched to CdX (X = S, Te) substrate alloys exhibits a semiconducting behavior with a small lattice mismatching ratio which might make Cd x Mg (1-x) Te y S (1-y) /CdX materials promising and useful for optoelectronic applications. • Investigate the structural, electronic, and optical properties of CdS, CdTe, MgTe and MgS in zinc-blende structure. • Investigate the structural, electronic and optical properties of Cd x Mg (1-x) Te y S (1-y) in zincblende structure. • Investigate the optical parameters quantitively. • The direct band-gaps for CdS, CdTe, MgTe and MgS are underestimated relate to the room-temperature experimental gaps. • The obtained wave lengths for Cd x Mg (1-x) Te y S (1-y) matched to CdX (X = S, Te) are obviously confined between 300 and 500 nm. [ABSTRACT FROM AUTHOR]

Motivated by experimental realization of honeycomb borophene (HB) on an Al(111) surface, we propose a non-orthogonal Slate-Koster tight binding (TB) model for single layer HB, of which parameters are optimized via a combination of the genetic algorithm and the simplex method using electronic structures obtained from density functional theory (DFT) as targets. Our proposed Slate-Koster parameters can well produce both energies and orbital compositions of electronic bands of a single layer HB. The direct calculation of band structure and atomic orbital resolved density of states show excellent agreement with DFT results. The highly accurate TB model would facilitate the future large-scale atomistic modeling on electronic, optical, and transport properties of HB based nano-materials. [ABSTRACT FROM AUTHOR]

Nonmagnetic germanides La TE 2 Ge 2 with TE  = Fe, Co, Ni, Cu and Ru were studied by means of X-ray diffraction, magnetization and electrical resistivity measurements performed down to 2 K, supplemented by fully relativistic band structure and Fermi surface calculations. Results of the theoretical investigations of all the compounds are in line with the experimental findings, namely they show decreasing influence of 3d-electrons of the Fe, Co, Ni and Cu atoms on the electronic properties with increasing the atomic mass. In the case of LaFe 2 Ge 2 the electrical resistivity measurements strongly suggest presence of spin fluctuations, which make that system very similar to the unconventional superconductor YFe 2 Ge 2 . [ABSTRACT FROM AUTHOR]

In this work, we present the first principles calculations for structural, electronic and optical properties of perovskites C a Z r O 3 and C a H f O 3 using the full-potential linearized augmented plane wave method (FP-LAPW) within the framework of density functional theory (DFT) as implemented in WIEN2k package. The exchange-correlation potential is treated with local density approximation (LDA) and generalized gradient approximation (GGA-PBE and PBESol). Additionally, the Tran Blaha modified Becke-Johnson exchange potential (mBJ) also is employed for electronic and optical calculations due to that it gives very accurate band gap of solids. Our obtained structural parameters are in good agreement with experimental datas and other theoretical results. The energy band gap obtained with mBJ is 4.56 eV for C a Z r O 3 and 5.27 eV for C a H f O 3 . The hybridization of states of O atom with those of Zr and Hf atoms in C a Z r O 3 and C a H f O 3 , respectively, is observed. The spin-orbit coupling effect on electronic properties of considered compounds also is investigated. Finally, the linear optical properties of C a Z r O 3 and C a H f O 3 are derived from their complex dielectric function calculated with mBJ potential for wide energy range up to 45 eV, and all of them analyzed in details. [ABSTRACT FROM AUTHOR]

In the framework of density functional theory based on plane wave pseudopotential method and linear response technique, we have studied the electronic, phonon and superconducting properties of LaPtBi half-Heusler compound. The electronic band structure and density of states show that it is gapless semiconductor which is consistent with previous results. The positive phonon frequencies confirm the stability of this compound in cubic MgAgAs phase. Superconductivity is studied in terms of Eliashberg spectral function (α 2 F(ω)), electron-phonon coupling constants (λ). The value of electron-phonon coupling parameter is found to be 0.41 and the superconducting transition temperature is calculated to be 0.76 K, in excellent agreement with the experimentally reported values. [ABSTRACT FROM AUTHOR]

It is predicted that the ZrCrCoZ(Z=B, Al, Ga, In) compounds with LiMnPbSn-type structure are half-metallic ferrimagnets with a large half-metallic gap by the first-principles calculations. The half-metallicity of the ZrCrCoZ(Z=B, Al, Ga, In) compounds are quite robust to the axial and uniaxial strain. The total magnetic moments in per unit cell are 4 μ B for the ZrCrCoZ(Z=B, Al, Ga, In) compounds and follow the Slater-Pauling rule, which can be attributed to the great spin-splitting. The calculated formation energies are negative for all the ZrCrCoZ(Z=B, Al, Ga, In) compounds, which indicates that those compounds are in the thermodynamic stability and the possibility of synthesis in experiment. [ABSTRACT FROM AUTHOR]

Band alignment in graphene-like III-nitride semiconductors was investigated using first principles calculations and an empirical formula. We estimated the band edge positions using two simple approaches based on the energy of the band gap center (BGC) and electron affinity rules. The energy positions relative to the vacuum level were determined from the BGC and Mulliken electronegativities. These methods provided similar trends in the band lineup. The valence band and conduction band offsets determined by the first principles calculations agreed with the empirical results to within 0.5 eV. The findings suggest that the first principles and empirical methods provide a useful guide for high-throughput device design. [ABSTRACT FROM AUTHOR]

First principles scalar relativistic (SR) calculations with and without including the spin orbit (SO) interactions have been performed for solid Copernicium (Cn) to determine its ground state equilibrium structure, volume, bulk modulus, pressure derivative of the bulk modulus, density of states and band structure. Both SR and SR+SO calculations have been performed with 6p levels treated as part of core electrons and also as part of valence electrons. These calculations have been performed for the rhombohedral, BCT, FCC, HCP, BCC and SC structures. Results have been compared with the results for Hg which is lighter homologue of Cn in the periodic table. We find hcp to be the stable crystal structure at SR level of theory and also at SR+SO level of theory when the 6p electrons are treated as part of core electrons. With 6p as part of valence electrons, SR+SO level of computations, however, yield bcc structure to be the most stable structure. Equilibrium volume (V 0 ) of the most stable crystal structure at SR level of theory viz. hcp structure is 188.66 a.u. 3 whereas its value for the bcc structure, the equilibrium ground state structure at SR+SO level of theory is 165.71 a.u. 3 i.e a large change due to relativistic effects is seen. The density of states at Fermi level is much smaller in Cn than in Hg, making it a poorer metal than mercury. In addition the cohesive energy of Cn is computed to be almost two times that of Hg for SR+SO case. [ABSTRACT FROM AUTHOR]

We have studied the influence of electron correlation energy ( U ) and exchange correlation energy ( J ) on the electronic structure of R VO 3 ( R = La and Y) compounds using all-electron full-potential linearized augmented plane wave method within density functional theory. Our calculated electronic band structure shows metallic character with generalized gradient approximation (GGA) formalism though LaVO 3 and YVO 3 are both known to be insulators with a band gap of 1.1 eV and 1.2 eV, respectively. Our GGA+U approach has succeeded in describing the correct ground state yielding insulating band structures for both LaVO 3 and YVO 3 . However, this insulating ground state is obtained by adjusting the parameter, U to reproduce the correct experimental band gap. To determine the optimal U value for the onsite coulomb potential, we have performed a series of GGA+U calculations by varying the U eff (difference between U and J ) parameter keeping J fixed. We have also varied the exchange parameter J , (though not as strong as that of U ) keeping U eff fixed to see its influence on the band gaps of LaVO 3 and YVO 3 and it has been shown that both the U and J have great impact on the electronic structure of these two compounds. [ABSTRACT FROM AUTHOR]

The electronic structures and thermal transport properties of the half-Heusler (HH) compounds LiMgN and LiZnN are calculated in detail by combining first-principles calculations with Boltzmann transport theory. Our phonon calculations showed that LiMgN and LiZnN are dynamic stability. The calculated bulk moduli and equilibrium lattice constants are in good agreement with the experimental and available theoretical data. The electronic band structures obtained by PBE (HSE06) method indicate that both LiMgN and LiZnN are direct bandgap semiconductors with band gaps of 2.33 eV (3.23 eV) and 0.53 eV (1.42 eV), respectively. It is shown that the Li–N，Li–Mg and Li–Zn are ionic bond via ELF analysis. At room temperature, the calculated lattice thermal conductivities of LiMgN and LiZnN compounds are 19.31 Wm−1K−1 and 18.74 Wm−1K−1, respectively; But with the external temperature increases to 1100 K, their lattice thermal conductivities are decrease rapidly to 4.96 Wm−1K−1 and 4.32 Wm−1K−1, respectively. Moreover, we analyzed the mean free paths, phase volume spaces (P 3), Gruneisen parameters (γ), scattering rates and group velocities in detail in order to further understand the origins of their relatively low lattice thermal conductivities and corresponding microscopic mechanism. We also investigated thermoelectric performances of LiMgN and LiZnN under different temperatures, and our results showed that with the external temperature increasing from 300 K to 1100 K, the maximum ZT values can increase from 0.05 (0.03) and 1.83 (1.32) for LiMgN (LiZnN), indicating that they are potential high-temperature thermoelectric materials. Our work can offer some theoretical references for improving thermoelectric performance and for future experimental studies. The HH compounds LiXN (X = Mg, Zn) are classified as direct bandgap semiconductors. Their respective lattice thermal conductivities at 1100 K are measured to be 4.96 Wm−1K−1 and 4.32 Wm−1K−1. Additionally, their maximum achieved ZT values are 1.83 and 1.32, respectively. [Display omitted] • The half-Heusler compounds LiMgN and LiZnN exhibit semiconductor behavior, characterized by direct band gaps. • At a temperature of 1100 K, the κ l of LiMgN and LiZnN is measured to be 4.96 Wm-1K-1 and 4.32 Wm-1K-1, respectively. • The maximum ZT values of 1.82 and 1.32 are predicted for the LiMgN and LiZnN at 1100 K. [ABSTRACT FROM AUTHOR]

Chemical doping is promising route to modify and control the electronic properties of graphene Nanosheet (GNS). The electronic properties of the GNS are investigated with and without various concentrations of phosphorus impurities in the various sites by using the first-principles of the density functional theory (DFT) method, which realized in Quantum Espresso packages. My founding results show that the electronic band structure of the GNS is not only depending on the concentrations of phosphorus impurities, but also depending on the geometrical pattern of phosphorus impurities in the GNS. Furthermore, I found out that there is an electronic band gap with a single phosphorus impurities and it is increased with increasing the concentrations of phosphorus impurities. Also, total energy is affected and decreased with increasing the concentrations of phosphorus impurities, which is led to make all structures are unstable and more reactive. Then, phosphorus impurities are significantly contributing to engineering, control and alter the electronic properties of the GNS, which is very important in various applications. [ABSTRACT FROM AUTHOR]

Motivated by recent discovery of a non-Fermi liquid behavior and unconventional superconductivity in YFe 2 Ge 2 we performed physical properties studies and fully relativistic band structure calculations for a few La-based silicides, namely LaFe 2 Si 2 , LaCo 2 Si 2 , LaAg 2 Si 2 and LaAu 2 Si 2 . Electrical resistivity and heat capacity measurements revealed decreasing influence of d -electrons of the transition elements on the conduction electron scattering and the Sommerfeld coefficient with increasing the atomic number. Band structure calculations fully corroborated the experimental findings. No superconductivity was found in the investigated compounds down to 0.35 K. [ABSTRACT FROM AUTHOR]

We theoretically investigated the physical properties of RhMnTiZ (Z = Si, Ge, Sn) compounds. The negative formation energies and the phonon dispersions indicate the structural and dynamical stability of RhMnTiZ (Z = Si, Ge, Sn) compounds. The result of electronic band structures shows that the RhMnTiZ (Z = Si, Ge, Sn) compounds have indirect band gaps with 0.60, 0.42 and 0.22 eV using mBJ-GGA, respectively. The various transport properties of the RhMnTiZ (Z = Si, Ge, Sn) compounds are calculated using Boltztrap code. The large Seebeck coefficient and power factor of RhMnTiZ (Z = Si, Ge, Sn) at positive chemical potential suggest that they are new promising candidates for n-type thermoelectric materials. • RhMnTiZ (Z = Si, Ge, Sn) compounds are new promising candidates for the thermoelectric materials. • The structure, dynamical stability, electronic band structure and transport properties have been performed. • The electronic structures show indirect band gap semiconducting nature. • ZT value is high for n-type doping concentration. [ABSTRACT FROM AUTHOR]

The structural, mechanical, thermal, electronic and optical properties of inorganic Pb-free double perovskites C s 2 T i X 6 (X = C l , B r , I) compounds are investigated. Using the first-principles with full-potential linearized augmented plane wave (FP-LAPW) method, supported the density functional theory, and therefore the generalized gradient approximation (GGA-PBE) and Hybrid exchange-correlation functionals with and without spin-orbit coupling. The computation of the lattice constants showed an honest agreement between our results and the experimental results and the theoretical data available. Using the three independent elastic constants C 11 , C 12 and C 44 , various mechanical and thermal properties are obtained such as: bulk modules B , shear modules G , Young's modules Y , Pough's ratio B / G , Frantesvich ratio G / B , Poisson's ratio υ , Shear anisotropy character A and Debye temperature Θ D for C s 2 T i I 6 , C s 2 T i B r 6 and C s 2 T i C l 6 respectively. Our calculated elastic constant results show that C s 2 T i I 6 , C s 2 T i B r 6 and C s 2 T i C l 6 are mechanically stable, anisotropic and ductile in nature. Furthermore, the C s 2 T i C l 6 compound has the highest Debye temperature, which indicates the highest melting temperature. The electronic band structures reveal the semiconductor conductivity of the three compounds, with a band gap suitable for photovoltaic applications, within the range of 1.5–2.96 e V. Finally, C s 2 T i C l 6 (X = C l , B r , I) HPs compounds exhibit excellent optical properties like optical absorption, conductivity and refraction index. • The calculated elastic constant results show that C s 2 T i I 6 , C s 2 T i B r 6 and C s 2 T i C l 6 are mechanically stable, anisotropic and ductile in nature. • The calculation of optimized lattice constants indicate that our results are in good agreement with the experimental data and theoretical data available. • The electronic band structures reveal the semiconductor conductivity of the three compounds, with a band gap suitable for optoelectronics applications. • The results of optical properties indicate that the C s 2 T i C l 6 (X = C l , B r , I) halide perovskites are a promising material for photoelectric conversion. [ABSTRACT FROM AUTHOR]

Based on density functional theory (DFT), the crystal structural and electronic properties of two cubic BiFeO 3 phases (Fd 3 ‾ m -BiFeO 3 and Pm 3 ‾ m -BiFeO 3) have been researched. Using USPEX based on ab initio evolutionary algorithm, the cubic crystal structure (Fd 3 ‾ m) was predicted at ambient pressure. The structural parameters of the ambient-pressure cubic phase Fd 3 ‾ m and the high-temperature cubic phase Pm 3 ‾ m are given in the paper. Through the calculation of phonon dispersion curves, it is found that the Fd 3 ‾ m phase has no imaginary frequency and can exist stably at ambient pressure. However, the Pm 3 ‾ m phase has imaginary frequency and cannot exist stably at ambient pressure. In electronic band structures, the finite value at the Fermi level are suggestive of the metallicity of Fd 3 ‾ m and Pm 3 ‾ m phases, in which the highest valence band overlap with the lowest conduction band. It is concluded that two cubic phases of BiFeO 3 are metal phases, which are different from the semiconductor properties of all BiFeO 3 isomers previously reported. Their Partial Density of States diagrams show that Bi-6p, Fe-3d and O-2p have obvious hybridization in the range of −5 eV – 5 eV. Besides, we researched their charge transfer and charge localization. Finally, we calculated their elastic properties and found that Fd 3 ‾ m -BiFeO 3 has higher Vickers hardness, which can extend the life of BiFeO 3 devices. This work provides a solid theoretical guidance for understanding the electronic structure of multiferroic materials. [ABSTRACT FROM AUTHOR]

In this work, we present a density functional theory study of the mechanical and electronic properties of silicon nanowires (SiNWs) grown along the [111] crystallographic direction with a diamond structure and surface passivated with hydrogen (H) and lithium (Li) atoms. The study is performed within the local density approximation by applying the supercell method. The results indicate that the energy gap is a function of the Li concentration and the nanowire diameter. Furthermore, the Young's modulus (Y) increases as the nanowire diameter increases, consistent with experimental reports. The increase in the Li concentration at the surface leads to a larger Y value compared to the Y value of the completely H-passivated SiNWs, except for the thinner nanowires. Moreover, the structure of the latter nanowires experiences important changes when the Li concentration increases up to the maximum Li atoms per cell. These results demonstrate that it is possible to simultaneously control the energy gap and the Young’s modulus by tuning the Li concentration on the surface of the SiNWs and could help to understand the structural changes that the silicon nanowire arrays experience during the lithiation process in Li batteries. [ABSTRACT FROM AUTHOR]

In this paper, we study the electronic properties of WSe 2 monolayer with biaxial tensile strain and compressive strain by using first principles based on the density function theory. Under the biaxial tensile strain, WSe 2 monolayer retains direct band gap with increasing strain and the band gap of WSe 2 continuously decreases with increasing strain, eventually turn to metal when strain is equal to or more than 13%. Under the biaxial compressive strain, WSe 2 monolayer turns to indirect gap and the band gap continuously decreases with increasing strain, finally turn to metal when strain is up to −7%. The strain can reduce the band gap of the WSe 2 monolayer regardless of the strain direction. By comparison, we can see that the tensile strain appears to be more effective in reducing the band gap of pristine WSe 2 monolayer than the compressive strain from −5% to 5%. But the band gap turns to zero quickly from −6% to −7% under compressive strain, however for tensile strain from 5% to 13%, the band gap decreases slowly. Based on the further analysis of the projected charge density for WSe 2 monolayer, the fundamental reason of the change of band structure under biaxial tensile strain is revealed. [ABSTRACT FROM AUTHOR]

In this paper, the thermoelectric, electronic and structural properties of lead-based chalcogenides PbX (X = O, S, Se, Te) and tellurium-based YTe (Y = Si, Ge, Sn, Pb) nano-layers were calculated using density functional theory. In this method, we used the ultrasoft pseudopotential and the GGA-PBE approximation to solve the Schrodinger equation. The electronic band structure results showed that the lead-based chalcogenides PbX nano-layers are semiconductors with a direct band-gap. The tellurium-based YTe nano-layers showed metallic behavior and among them only PbTe nano-layers is a semiconductor. The thermoelectric properties of these materials were calculated using Boltzmann's semi-classical theory in the temperature range of 300–800 K. Thermoelectric results showed that, lead-based nanolayers have higher thermoelectric proprties than tellurium-based compounds. • YTe (Y Si, Pb, Sn, Ge) and PbX (X = O, S, Se, Te) nano-layers is highly recognized as potential thermoelectric material. • The Seebeck coefficient decreased with increasing temperature. • Thermal conductivity increased with an increase in chemical potential. • The electronic structures are calculated using the plane wave pseudopotential method within the GGA method. [ABSTRACT FROM AUTHOR]

We investigate the electronic and magnetic properties of Cr-Mn-Ni-Al compound with a LiMgPdSn-type structure in three different atomic arrangement configurations (AAC) by using the first-principles calculations. It was found that Cr-Mn-Ni-Al compound with type I AAC exhibits a spin-gapless semiconductive characteristic. The type II AAC is the most stable one and exhibits an especial band structure where the Fermi level slightly crosses the top of the valence bands in spin-up channel and the bottom of conductive bands in spin-down channel, which leads to the electronic transport with the spin-resolved carrier type. The Cr-Mn-Ni-Al compound shows an ordinary metallic behavior in type III AAC. The three nonequivalent atomic arrangement configurations of Cr-Mn-Ni-Al are all in ferromagnetic ground state under their equilibrium lattice parameters. [ABSTRACT FROM AUTHOR]

Using ab-initio the Full-Potential Local Orbital minimum basis (FPLO) and Vienna Simulation Package (VASP) methods in the framework of the local density functional theory within the generalized gradient approximation (GGA) the band structure and thermodynamic properties of aurates BaAu 2 O 4 , SrAu 2 O 4 and BaSrAu 2 O 4 have been studied. Ab-inito calculations have shown that these systems are semiconductors with the gap between 1.42 and 1.65 eV. The values of gaps decrease with the increase of the volume. The thermodynamic parameters (bulk modulus and Debye temperature) are calculated in the quasi-harmonic Debye–Grüneisen model. Both ab-initio methods give the similar results. [ABSTRACT FROM AUTHOR]

In this paper, we consider the optimum coordinate of the penta-graphene. Penta-graphene is a new stable carbon allotrope which is stronger than graphene. Here, we compare the band gap of penta-graphene with various density functional theory (DFT) methods. We plot the band structure of penta-graphene which calculated with the generalized gradient approximation functional HTCH407, about Fermi energy. Then, one-shot GW ( G 0 W 0 ) correction for precise computations of band structure is applied. Quasi-direct band gap of penta-graphene is obtained around 4.1–4.3 eV by G 0 W 0 correction. Penta-graphene is an insulator and can be expected to have broad applications in future, especially in nanoelectronics and nanomechanics. [ABSTRACT FROM AUTHOR]

First-principles calculations were performed to investigate the electronic and magnetic properties of Ti 3 C 2 monolayer and its derivatives. We found that pristine Ti 3 C 2 monolayer acts as a magnetic metal, and magnetic moments come from Ti 2+ ions at two sides. Through doping nitrogen atoms, the spin moments is significantly reduced. On other hand, when two surfaces of Ti 3 C 2 monolayer are saturated by external groups, the magnetism will be spontaneously annihilated. Even for the saturation of one side, we also found that the magnetism of Ti 3 C 2 Y (Y is O and OH) monolayer is removed because of the invalidation of stoner instability. More importantly, we explored that both doping and surface modification will reduce the Curie temperature of Ti 3 C 2 monolayer. Therefore, our results shed a light on the way to get high-temperature magnetism in Ti 3 C 2 monolayer. [ABSTRACT FROM AUTHOR]

The electronic behavior of the long disordered DNA nanowires in both dry and wet conditions is investigated through the band structure and density of states of a tight-binding Hamiltonian model for π -electrons of the backbone, using Green׳s functions approach. For a chosen set of parameters in the dry case, semiconducting behavior is reproduced. It is also shown that for sufficiently long strands, the order of the base pairs has no noticeable effect on the energy band-gap. Moreover, this semiconducting duplex shows metallic tendencies when interacting with the environment of polar molecules. [ABSTRACT FROM AUTHOR]

Similar to graphene, two-dimensional germanene possesses a honeycomb structure and Dirac cone in its band structure. Being inspired by these similarities, we have studied the electronic structure as well as spin Hall conductivity of germanene supported by monolayers of four monochalcogenides, namely, GaS, GaSe, GaTe, and InSe. By using the first principle calculations based on density functional theory we have investigated the structural stability, buckling of germanene, and electronic band structures of these systems with and without spin–orbit interactions. All the four systems possess Dirac cone in their band structures, but germanene on GaTe and InSe substrates become nonmetallic with very small band gaps of ∼ 28–70 meV. He calculated spin Hall conductivity and the nature of the edge states drive us to infer that germanene, supported by monolayered GaTe or InSe, is a spin Hall insulator with a nontrivial bandgap. • Density functional theory including spin orbit coupling. • Sustainable Dirac gap of germanene supported by monolayer (ML) of monochalcogenides. • Surface states of germanene on GaTe and InSe predict the topological insulating nature. • All the systems considered here exhibit spin Hall conductivity (SHC) at the Fermi level. [ABSTRACT FROM AUTHOR]