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Periodic density functional theory was employed to investigate the impact of chemical modifications on the properties of π-conjugated acenedithiophene molecular crystals. Here, we highlight the importance of the β-methylthionation effect, the position of the sulfur atoms of the thiacycle group and their size, and the number of central benzene rings in the chemical modification strategy. Our results show that the introduction of the methylthio groups at the β-positions of the thiophene and the additional benzene ring at the center of the BDT crystal structure are a promising strategy to improve the performance of organic semiconductors, as observed experimentally. We found that β-MT-ADT exhibits large charge carrier mobility, which is in good agreement with the experimental results and comparable to that of rubrene. In addition, the electronic and optical properties of these ambipolar materials suggest promising performances with β-MT-ADT > ADT > β -MT-NDT > NDT > BEDT-BDT > β -MT-BDT > BDT. Moreover, functionalization with thiacycle-fused sulfur atoms of different sizes and numbers improve the properties of BDT but is still less efficient than the methylthionation effect. Overall, our findings suggest a promising molecular modification strategy for possibly high performance ambipolar organic semiconducting materials. [ABSTRACT FROM AUTHOR]

The absorption spectra of congenetic wurtzite (WZ) and zincblende (ZB) CdS magic-sized clusters are investigated. We demonstrate that the exciton peak positions can be tuned by up to 500 meV by varying the strong coupling between X-type ligands and the semiconductor cores, while the addition of L-type ligands primarily affects cluster midgap states. When Z-type ligands are displaced by L-type ligands, red shifts in the absorption spectra are observed, despite the fact there is a small decrease in cluster size. Density functional theory calculations are used to explain these findings and they reveal the importance of Cd and S dangling bonds on the midgap states during the Z- to L-type ligand exchange process. Overall, ZB CdS clusters show higher chemical stability than WZ clusters but their optical properties exhibit greater sensitivity to the solvent. Conversely, WZ CdS clusters are not stable in a Lewis base-rich environment, resulting in various changes in their spectra. Our findings enable researchers to select capping ligands that modulate the optical properties of semiconductor clusters while maintaining precise control over their solvent interactions. [ABSTRACT FROM AUTHOR]

In this article, the properties of Cs2Pb2O3 have been investigated using the first‐principles method. It covers the relevant structural, stability, electronic properties, conductivity, and optical properties. The phonon spectra and elastic properties analysis show the stability of Cs2Pb2O3, band structure, density of states, charge density diagram, and bond populations are analyzed to show the electronic structure of the system more clearly. The calculated results indicate that considering spin‐orbit coupling (SOC) will reduce the band gap. The charge density diagram and bond populations indicate that the Cs–O bond is mainly ionic and the Pb–O bond is mainly covalent and partially ionic. The analysis of optical properties indicates good transparency, and the calculated hole mobility is 10.88 cm2 V−1 s−1, suggesting that it is a promising p‐type conductive oxide. [ABSTRACT FROM AUTHOR]

We designed and synthesized 1,1′,3,3′-tetraaryl-4,4′-bibenzo[c]thiophene derivatives, 1,1′,3,3′-PhtBu-4,4′-BBT (BBT-PhtBu4), 1,1′,3,3′-PhCN-4,4′-BBT (BBT-PhCN4), and 1,1′-PhtBu-3,3′-PhCN-4,4′-BBT (BBT-PhtBu2PhCN2), which have four electron-donating tert-butylphenyl groups, four electron-withdrawing cyanophenyl groups, and two tert-butylphenyl groups and two cyanophenyl groups, respectively, on each thiophene ring by the Stille coupling reaction using 1,1′-diaryl-3,3′-distannyl-4,4′-BBT or 1,1′,3,3′-tetrastannyl-4,4′-BBT. It was found that the photoabsorption and fluorescence maximum wavelengths (λabsmax and λflmax) of BBT-PhtBu4, BBT-PhCN4, and BBT-PhtBu2PhCN2 appear in a longerwavelength region, in comparison with those of 1,1′-diaryl-4,4′-BBT derivatives BBT-PhtBu2 with a tert-butylphenyl group and BBT-PhCN2 with a cyanophenyl group on each thiophene ring. Moreover, the cyclic voltammetry (CV) curves of the 4,4′-BBT derivatives indicated that the introduction of the electron-donating tert-butylphenyl group and/or the electron-withdrawing cyanophenyl group into the benzo[c]thiophene skeleton leads to the lowering of the oxidation potential. In addition, an electron-donating phenyl substituent is more effective than an electron-withdrawing phenyl substituent in the lowering of the oxidation potential. Density functional theory (DFT) calculations as well as the experimental results revealed that increasing the number of electron-donating and electron-withdrawing phenyl groups on the thiophene ring results in the increase of the HOMO energy level and the lowering of the LUMO energy level, respectively, that leads to a decrease in the HOMO–LUMO band gap, that is, a bathochromic shift of the photoabsorption band. Thus, this work provides not only facile synthetic methods for 1,1′,3,3′-tetraaryl-4,4′-BBT derivatives with the same or different aryl substituents on the thiophene rings but also useful methods to precisely adjust their optical and electrochemical properties. [ABSTRACT FROM AUTHOR]

Employing functional building units with microscopic second‐order NLO response has been proposed to explore high performance NLO materials. Herein, structural, electronic and optical properties of non‐centrosymmetric molybdenyl carbonate Cs3MoO4(HCO3) with NLO active functional units have been examined based on density functional theory. Theoretical results are consistent with experimentally mentioned data, confirming the reliable method. Detailed geometric structure, electronic attributes, linear optical properties, and nonlinear optical properties of Cs3MoO4(HCO3) are provided. Analysis of structures, compositions of bands and plots of charge density suggest that asymmetric functional building units [MoO4] and [HCO3] exhibit varying degrees of second‐order Jahn‐Teller distortions, and therefore have a significant impact on the electronic structure and optical properties of Cs3MoO4(HCO3). Maximum absolute value of SHG coefficients at 1064 nm is 0.671 pm/V for d15, which is nearly twice as much as that of KDP. Further researches are needed in future to validate and enhance optical anisotropy characteristic of Cs3MoO4(HCO3) for satisfying the phase matching conditions. Analysis results indicate that microscopic origins of SHG response in Cs3MoO4(HCO3) are complicated, such as geometric environment, induced polar asymmetric functional building units, and electronic properties. Continuous research on structure‐property relationship of NLO materials is needed for exploring more competitive NLO materials. [ABSTRACT FROM AUTHOR]

Context: This investigation includes the structural and optoelectronic characteristics of both pure and Er-doped rock salt aluminium nitride (AlN). Upon introducing Er doping into the AlN host, the calculations reveal a rise in the atomic parameter. Incorporating Er into the system leads to enhancements in the static dielectric coefficient ɛ1(0), static reflectivity R(0), as well as static refractive index n(0), at zero frequency. After doping, the peaks of imaginary dielectric tensor, extinction coefficient and absorption coefficient shift towards lower energy levels. Various exchange correlation potentials are incorporated to compare the results of electronic and optical characteristics. Methods: We employed the full potential linearized augmented plane wave (FP-LAPW) approach with WIEN2k code in conjunction with the density functional theory (DFT). To explore the optoelectronic characteristics of both pure as well as doped systems, three distinct exchange correlation potentials are utilized: the Perdew-Burke-Ernzerhof Generalized Gradient Approximation (PBE-GGA), Modified Becke Johnson Generalized Gradient Approximations (mBJ + GGA) and Hubbard potential (GGA + U). [ABSTRACT FROM AUTHOR]

The structural, electronic, magnetic, and optical properties of Co-doped 10–20-atom silver clusters are investigated by GGA/PBE via the density functional theory. The Ag–Co clusters form core–shell structures with a Co atom in the center. Co atom doping modulates electronic properties like energy gap, molecular softness, global hardness, electronegativity, and electrophilicity index. For the optical spectra of the Ag–Co clusters, the energy of their spectra overall exhibits little change with increasing numbers of atoms; the strongest peaks are roughly distributed at 3.5 eV, and the intensity of their spectra overall is strengthened. Raman and vibrational spectra reflect structural changes with Co atom addition. The addition of the Co atom alters magnetic moments of specific Ag–Co clusters, while others remain unchanged. [ABSTRACT FROM AUTHOR]

First principles calculations of the structural, electronic and optical properties of GaSb, InSb and their ternary Ga 1 - x In x Sb alloys (x = 0.25, 0.50 and 0.75) have been performed using the full-potential linear muffin-tin orbital (FP-LAPW) method within density functional theory (DFT). The generalized gradient approximation and modified Becke and Janson functional with local density approximation (mBJ–LDA) are utilized for the treatment of exchange and correlation potentials. The results show the calculated lattice constants increase linearity with increasing the In concentration. The electronic band structure indicates that these alloys are direct band gap semiconductors for all the values of x and the band gap decreases as x increases from x = 0 to x = 1. The results also show that the there is a non-linear dependence of the band gap on composition x in Ga 1 - x In x Sb alloys. Regarding optical properties, the real and imaginary parts of the dielectric function have been calculated. The results show that the static dielectric constant increases with increase in concentration of In, consistent with reduction in energy band gap. The onset point and major peaks in the imaginary parts of the dielectric function spectra are identified for the Ga 1 - x In x Sb alloys and shown that they are related to the corresponding band gap values. The results also show that for energy values higher than ≅ 4 eV, the electromagnetic wave transition through Ga 1 - x In x Sb alloys is nearly zero. [ABSTRACT FROM AUTHOR]

Double traditional metal (TM) Janus MXenes have more superior properties when compared with MXenes. The electronic and optical properties, Bader charge and quantum capacitance of ZrMCO 2 (M = Sc, Ti, V, Cr, Mn, Fe, Y, Zr, Nb, Mo, Hf, Ta, W) are explored by density functional theory (DFT). The stability of these systems is confirmed by cohesive energy. The substitution of Ti/Hf atoms results in the decrease of bandgap of ZrTiCO 2 /ZrHfCO 2 , which is induced by the redshift of conduction band minimum (CBM). ZrMCO 2 (M = Cr, Mn) are magnetic semiconductors and ZrMCO 2 (M = Sc, V, Y, Fe) are magnetic metals. All doping atoms except Hf improve the maximum quantum capacitance of ZrMCO 2 at positive bias. Wide voltage makes ZrMCO 2 (M = Nb, Ta, W) change into anode material and ZrFeCO 2 into cathode material. ZrMCO 2 (M = Sc, Mn, Y, Hf, Zr) and ZrMCO 2 (M = V, Cr) can serve as cathode and anode materials in whole voltage, respectively. Much charge accumulating between Fe and C atoms results in the smallest Fe–C bond among all M − C bonds, which indicates the strongest interaction between Fe and C atoms. Optical properties and work function are further explored. [ABSTRACT FROM AUTHOR]

Chemical modification is a powerful strategy for tuning the electronic properties of 2D semiconductors. Here we report the electrophilic trifluoromethylation of 2D WSe2 and MoS2 under mild conditions using the reagent trifluoromethyl thianthrenium triflate (TTT). Chemical characterization and density functional theory calculations reveal that the trifluoromethyl groups bind covalently to surface chalcogen atoms as well as oxygen substitution sites. Trifluoromethylation induces p‐type doping in the underlying 2D material, enabling the modulation of charge transport and optical emission properties in WSe2. This work introduces a versatile and efficient method for tailoring the optical and electronic properties of 2D transition metal dichalcogenides. [ABSTRACT FROM AUTHOR]

Long‐life room temperature phosphorescent (RTP) materials hold significant potential in the fields of optoelectronic devices, information encryption, and bio‐imaging due to their excellent optical properties. However, achieving multi‐color tunable RTP materials has proven challenging. In this study, molecular engineering strategies are employed to select precursor molecules with varying degrees of conjugation such as phthalic anhydride (PA), naphtho[2,3‐c] furan‐1,3‐dione (23NA), and naphthalic anhydride (NA). By combining these guest molecules with a host boric acid matrix through a one‐step microwave method, carbon dots (CDs)composites (PA@BA, 23NA@BA and NA@BA) exhibiting excellent RTP properties are successfully prepared. As the degree of precursor conjugation increased gradually, the phosphorescence color modulation of the composites demonstrates satisfactory transitions from blue to yellow. Notably, CDs are derived in situ within the boric acid matrix while covalent and hydrogen bonds formed between CDs and borate matrix effectively suppress nonradiative leaps and facilitate composite RTP activation. Furthermore, the boric acid matrix acts as insulation against oxygen diffusion and prevents quenching of triplet excitons by external factors. The rationality behind phosphorescence emission mechanism and wavelength modulation is further conformed by density functional theory (DFT) calculations. Finally, CDs composites are successfully applied for advanced message encryption of text and images. [ABSTRACT FROM AUTHOR]

Chemical modification is a powerful strategy for tuning the electronic properties of 2D semiconductors. Here we report the electrophilic trifluoromethylation of 2D WSe2 and MoS2 under mild conditions using the reagent trifluoromethyl thianthrenium triflate (TTT). Chemical characterization and density functional theory calculations reveal that the trifluoromethyl groups bind covalently to surface chalcogen atoms as well as oxygen substitution sites. Trifluoromethylation induces p‐type doping in the underlying 2D material, enabling the modulation of charge transport and optical emission properties in WSe2. This work introduces a versatile and efficient method for tailoring the optical and electronic properties of 2D transition metal dichalcogenides. [ABSTRACT FROM AUTHOR]

A new noncentrosymmetric strontium borate, P1‐Sr2[B5O8(OH)]2 ⋅ [B(OH)3] ⋅ H2O (1), has been synthesized under the hydrothermal condition. The P1‐Sr2[B5O8(OH)]2 ⋅ [B(OH)3] ⋅ H2O shows a layered B−O network with 9‐ring windows in the ab plane. Sr2+ cations, H3BO3, and H2O molecules are located in the voids of layers and interlayers, respectively. The P1‐Sr2[B5O8(OH)]2 ⋅ [B(OH)3] ⋅ H2O is the first synthetic phase of veatchite, while the other three polymorphs are found in different natural minerals. This strontium borate is a potential deep‐ultraviolet‐transparent nonlinear‐optical (NLO) crystal whose second‐harmonic‐generation (SHG) intensity is 1.7 times that of KH2PO4 (KDP) and is phase‐matchable. The short wavelength cutoff edge of compound 1 is below 190 nm. Density functional theory (DFT) calculations show that the B−O units are responsible for the nonlinear optical property. [ABSTRACT FROM AUTHOR]

The effective calculation of static nonlinear optical properties requires a considerably high accuracy at a reasonable computational cost, to tackle challenging organic and inorganic systems acting as precursors and/or active layers of materials in (nano‐)devices. That trade‐off implies to obtain very accurate electronic energies in the presence of externally applied electric fields to consequently obtain static polarizabilities (αij) and hyper‐polarizabilities (βijk and γijkl). Density functional theory is known to provide an excellent compromise between accuracy and computational cost, which is however largely impeded for these properties without introducing range‐separation techniques. We thus explore here the ability of a modern (double‐hybrid and range‐separated) Range‐Separated eXchange Quadratic Integrand Double‐Hybrid exchange‐correlation functional to compete in accuracy with more costly and/or tuned methods, thanks to its robust and parameter‐free nature. [ABSTRACT FROM AUTHOR]

The electronic and optical properties of hydrogenated silicene at different torsion angles are investigated using the density functional theory (DFT). It was found that when silicene was hydrogenated, the Si atoms were pulled out of plane due to covalent interactions between the Si and H atoms, increasing their flexural height to 0.731 Å. Torsional deformation decreases the structural stability of hydrogenated silicene and its adsorption energy decreases with increasing twist angle. Under the effect of torsion deformation, the bandgap of hydrogenated silicene increases and then decreases. The bandgap is 2.168 eV at a torsion angle of 0∘, indicating a wide bandgap semiconductor. Mulliken's charge population analysis shows that charge transfer occurs between Si–H atoms, with Si atoms losing electrons and becoming positively charged and H atoms gaining electrons and becoming negatively charged. From the analysis of optical properties, the torsional deformation induced the maximum absorption and reflection peaks of all the hydrogenated silicene systems to appear in the ultraviolet region. Compared with the system without torsional deformation, these peaks exhibit varying degrees of red and blue shifts. The above findings provide guidance for the application of silicene in nanooptoelectronic devices. [ABSTRACT FROM AUTHOR]

Dansyl chloride (DNS-Cl) is a fluorescence-labeled organic compound widely used in fields such as pharmacology, toxicology, organic synthesis and biochemistry. We perform a computational study of the structural, electronic, optical and vibrational properties of its orthorhombic crystalline form. We use the pseudopotential approach of the density functional theory (DFT) considering the generalized gradient approximation with dispersion correction (GGA + TS), the local density approximation (LDA) and the hybrid exchange-correlation functional HSE06. The band structure shows a direct gap in all approaches. Optical properties are calculated considering polarization along the polycrystal direction with the main features correlated to the band structure. Further, vibration modes, infrared (IR) and Raman spectra are also obtained and analyzed. [ABSTRACT FROM AUTHOR]

Lead-free K0.5Bi0.5TiO3 (KBT) ceramics with high density (~5.36 g/cm3, 90% of X-ray density) and compositional purity (up to 90%) were synthesized using a solid-state reaction method. Strongly condensed KBT ceramics revealed homogenous local microstructures. TG/DSC (Thermogravimetry-differential scanning calorimetry) techniques characterized the thermal and structural stability of KBT. High mass stability (>0.4%) has proven no KBT thermal decomposition or other phase precipitation up to 1000 °C except for the co-existing K2Ti6O13 impurity. A strong influence of crystallites size and sintering conditions on improved dielectric and non-linear optical properties was reported. A significant increase (more than twice) in dielectric permittivity (εR), substantial for potential applications, was found in the KBT-24h specimen with extensive milling time. Moreover, it was observed that the second harmonic generation (λSHG = 532 nm) was activated at remarkably low fundamental beam intensity. Finally, spectroscopic experiments (Fourier transform Raman and far-infrared spectroscopy (FT-IR)) were supported by DFT (Density functional theory) calculations with a 2 × 2 × 2 supercell (P42mc symmetry and C4v point group). Moreover, the energy band gap was calculated (Eg = 2.46 eV), and a strong hybridization of the O-2p and Ti-3d orbitals at Eg explained the nature of band-gap transition (Γ → Γ). [ABSTRACT FROM AUTHOR]

The work aims to investigate the nonlinear optical (NLO) activity of piperazine‐1,4‐diium acetate (PAA) molecule utilizing computational techniques. The computational calculations are performed using density functional theory (DFT) to explore the vibrational modes, electronic and NLO properties of PAA by comparing them with piperazine and acetic acid molecules. The natural bond orbital analysis is performed to identify hydrogen bonding and charge transfer interaction. A vibrational analysis is carried out and the assignment of fundamental modes is done using the vibrational energy distribution analysis (VEDA) program. Molecular electrostatic potential, frontier molecular orbital, electron localization function, localized orbital locator and Fukui analysis are carried out to identify chemical reactivity and charge transfer interaction. The UV–visible analysis is performed to obtain the electronic absorption spectrum. The hole–electron analysis is performed for the first five excitations to identify the type of excitation. The atoms in molecules, reduced density gradient and independent gradient model are performed to identify the hydrogen bonding, steric and van der Waals interactions. Hirshfeld analysis is performed to explore the intermolecular interactions within the PAA molecule. The NLO calculation is performed to evaluate the NLO parameters. The obtained results show that the PAA molecule is suitable for NLO applications. [ABSTRACT FROM AUTHOR]

In the presented work, we propose a systematic investigation of the electronic and optical properties of MnGa2Se4 by combining the spectroscopic ellipsometry carried out at room temperature in the spectral range of 1–4 eV and density functional theory (DFT) calculations. Ellipsometric measurements were collected at an incidence angle between 60° and 75° with a 5° step. The optical direct gap energies of MnGa2Se4 were estimated from the linear extrapolation of the absorption coefficients that were verified by band structure calculation. DFT calculation of the imaginary part ɛ shows that first critical point occurs at 2.46 eV and represents the direct optical transition at Γ point. The total magnetic moment of compound is 3.38 mB. The major contribution in total magnetic moment is due to 3d state of Mn atoms. [ABSTRACT FROM AUTHOR]

Context: As new materials, the ternary chalcogenides have recently brought scientists' attention. These materials are a novel class of semiconducting chemical compounds. They allow the increase of the photo-conversion efficiency, the performance, and the cheap energy cost. Such materials also provide a wide range of physical and chemical applications. Methods: The used investigation employs Density Functional Theory (DFT) implemented in the Wien2k package to systematically characterize the physical properties of ternary chalcogenide compounds XBiSe2 (X = Li, Na and K). Such method emphasizes their applicability to energy conversion technologies. Scrutinizing their electronic, optical, and thermoelectric properties elucidates the effect of alkali metal substitution on performance metrics. The results not only advance knowledge of these materials' physicochemical behaviors but also reveal their potential for tailored functionalization in next-generation energy and optoelectronic systems, marking a significant stride in material science and application-oriented research. [ABSTRACT FROM AUTHOR]

Context: The 2D AlN/BN planer heterostructure is a promising wide band gap semiconductor, but systematic studies of its bandgap and optical characteristics under applied strain are scarce. Here, the engineering property of 2D AlN/BN comprising bandgap nature transition and optical absorption capability (from unstrained to strained) have been investigated using density functional theory calculations. The formation energy calculations confirm the stability of the simulated nanoheterostructure. The electronic band structure calculations demonstrate that nanoheterostructure is an indirect bandgap material with a large bandgap of 5.26 eV, which can be modified effectively by applying strain. According to the calculations, the transition from indirect to direct band gap behavior has been observed at +15% biaxial strain with 2.71 eV band gap energy. Meanwhile, calculations for optical absorption and dielectric function reveal that the system has significant absorption peaks in the ultraviolet region which are very sensitive to applied strain. As strain increases, the first absorption peaks are shifted towards a lower energy range from 5.73 eV (Ꜫ= 0 %) to 3.76 eV (Ꜫ = +15%), which features an enhancement of optical absorption for solar and solar-blind regions. Furthermore, we determined that the band edge positions in 2D AlN/BN straddled the water redox potential under strain, indicating its effectiveness as a proficient photocatalyst. These characteristics make 2D AlN/BN planer nanoheterostructure a promising candidate for applications in optoelectronics and photocatalytic water splitting performance. Methods: First principles computations based on density functional theory were employed to carry out all the calculations with a self-consistent approach. For solving the Kohn-Sham equations, the first principles dependent full-potential linearized augmented plane wave scheme were adopted. For addressing the exchange-correlation effects, the generalized gradient approximation of PBEsol functional was used. To prevent interaction between the periodic images, we have inserted a vacuum region of 10 Å in the z-direction. Non-negligible weak dispersion corrections in nanoheterostructure were considered by using the DFT-D3 method of Grimme's. The locally modified Becke-Johnson (lmBJ) exchange potential has also been applied to compute electronic and optical properties in this research to obtain more accurate information. [ABSTRACT FROM AUTHOR]

Context: The electronic properties and optical properties of Cr-doped monolayer WS2 under uniaxial compressive deformation have been investigated based on density functional theory. In terms of electronic structure properties, both intrinsic and doped system bandgaps decrease with the increase of compression deformation, and the values of the bandgap under the same compression deformation after Cr doping are reduced compared with the corresponding intrinsic states. When the compressive deformation reaches 10%, both the intrinsic and doped system band gaps are close to zero. New electronic states and impurity energy levels appear in the WS2 system when doped with Cr atoms. For the optical properties, the calculation and analysis of the dielectric function under each deformation regime of monolayer WS2 show that the compression deformation affects the dielectric function, and when the compression deformation is 10%, the un-doped and Cr-doped regimes show a decrease in ε1(ω) compared to the compression deformation of 8%. For each deformation system, the peak reflections occur in the ultraviolet region. Near the position where the second peak of the absorption spectrum appears, it can be seen that the ability of each system to absorb light gradually decreases with the increase of the amount of deformation and appears to be red-shifted to varying degrees. Methods: This study follows the initial principles of the density functional theory framework and is based on the CASTEP module of Materials-Studio software GGA and PBE generalizations are used to perform computations such as geometry optimization of the model. We have calculated the energy band structure of monolayer WS2 with intrinsic and compressive deformations of 2% and 4% using PBE and HSE06, respectively. The band gap values calculated using PBE are 1.802 eV, 1.663 eV, and 1.353 eV, respectively, and the band gap values calculated with HSE06 are 2.267 eV, 2.034 eV, 1.751 eV. The results show that the bandgap values calculated by HSE06 are significantly higher than those calculated by PBE, but the bandgap variations calculated by the two methods have the same trend, and the shape characteristics of the energy band structure are also the same. However, it is worth noting that the computation time required for the HSE06 calculation is much longer than that of the PBE, which is far beyond the capability of our computer hardware, and the purpose of this paper is to investigate the change rule of the effect of deformation on the bandgap value, so to save the computational resources, the next calculations are all calculated using the PBE. The Monkhorst–Pack special K-point sampling method is used in the calculations. The cutoff energy for the plane wave expansion is 400 eV, and the K-point grid is assumed to be 5 × 5 × 1. Following geometric optimization, the iterative precision converges to a value of less than 0.03 eV/Å for all atomic forces and at least 1 × 10−5 eV/atom for the total energy of each atom. The vacuum layer's thickness was selected at 20 Å to mitigate the impact of the interlayer contact force. [ABSTRACT FROM AUTHOR]

Context: Two-dimensional (2D) nanoheterostructures of materials, integrating various phase or materials into a single nanosheet have stimulated large-scale research interest for designing novel two dimensional devices. In contemporary analysis present work, we examined the structural and electronic properties of the isolated 2D BN and GaN monolayers. We have investigated the structural stability and optoelectronic and photocatalytic response of the g-GaN/BN nanoheterostructure along with its response to strain. Nanoheterostructure g-GaN/BN is predicted to be a direct bandgap semiconductor with wide gap of 4.45 eV, whose value can be effectively modulated by applied strain ( ϵ) , ranging from 4.55 (ϵ = − 4%) to 3.58 eV (ϵ = 8%). We also discovered that the tensile strain of 8% can substantially tune the direct bandgap of nanoheterostructure to indirect band gap nature. Even more important, the biaxial tensile strain engineering accentuates an enhancement of optical absorption in the UV region, broadening the light harvesting of the g-GaN/BN nanoheterostructure with the shifting of first absorption peak from 4.64 (ϵ = − 4%) to 3.71 eV (ϵ = 8%). Furthermore, strain-tuned band edge potentials arrangement perfectly fits the water reduction and oxidation redox potentials. Our findings portend that the g-GaN/BN nanoheterostructure has application in prospective nanoscale optoelectronic devices and photocatalytic hydrogen evolution system. Methods: First principles calculations in this study are performed using density functional theory. Generalized gradient approximation within PBEsol functional employed to address the electron–electron exchange–correlation effects. For avoiding periodic interactions between the layers, we have inserted a vacuum region of thickness 10 Å in the z-direction. For ensuring the convergence accuracy of the computed results, convergence criteria of the iteration process is set to be 0.0001 eV. Local modified Becke–Johnson, a semi local functional, is applied for calculating electronic and optical properties for more accuracy of results. As in layered 2D nanoheterostructure, a factual depiction of the van der Waals interactions cannot be provided by conventional DFT techniques. Accordingly, in order to incorporate these interactions, we had employed the dispersion correction method of Grimme's. [ABSTRACT FROM AUTHOR]

Context: 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. Methods: 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 15 Å 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 500 eV, and the energy difference between the calculations given in the literature Reyes-Serrato et al. J Phys Chem Solids 59:743-6, 1998 using 550 eV was less than 0.01 eV, verifying the reliability of the data at a truncation energy of 500 eV. 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 × 10−6 eV, and the iterative accuracy convergence value is not less than 1.0 × 10−5 eV/atom for the total force of each atom and less than 0.03 eV/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. [ABSTRACT FROM AUTHOR]

Context: The crystal and molecular structure, electronic properties, optical parameters, and elastic properties of a 1:2 hexanitrohexaazaisowurtzitane (CL-20)/2-mercapto-1-methylimidazole (MMI) cocrystal under 0 ~ 100 GPa hydrostatic pressure were calculated. The results show that the cocrystal CL-20/MMI undergoes three structural transitions at 72 GPa, 95 GPa, and 97 GPa, respectively, and the structural transition occurs in the part of the MMI compound. Structural mutations formed new bonds S1-S2, C2-C7, and N1C5 at 72GPa, 95 GPa, and 97 GPa, respectively. Similarly, the formation of new bonds is confirmed on the basis of an analysis of the changes in lattice constants, cell volumes, and partial densities of states (PDOS) for S1, S2, C2, C7, N1, and C3 at the corresponding pressures. The optical parameters show that the pressure makes the peaks of various optical parameters of CL-20/MMI larger, and the optical activity is enhanced. The optical parameters also confirm the structural mutation of CL-20/MMI under the corresponding pressure. Method: CL-20/MMI was calculated by using the first-principles norm-conservative pseudopotential based on density functional theory (DFT) in the CASTEP software package. For the optimization results, the Broyden–Fletcher–Goldfarb–Shanno (BFGS) method is selected to optimize the geometry of the cocrystal in the range of 0–100 GPa. GGA/PBE (Perdew–Burke–Ernzerhof) was selected to relax the cocrystal CL-20/MMI fully without constraints at atmospheric pressure. The sampling scheme in the Brillouin zone [10] is the Monkhorst–Pack scheme, and the number of k-point grids was 2 × 2 × 2. By contrast, this study will use the LDA method to calculate. [ABSTRACT FROM AUTHOR]

This study presents the synthesis and characterization of oxonitridosilicate phosphates Sr3SiP3O2N7, Sr5Si2P4ON12, and Sr16Si9P9O7N33 as the first of their kind. These compounds were synthesized under high‐temperature (1400 °C) and high‐pressure (3 GPa) conditions. A unique structural feature is their common fundamental building unit, a vierer single chain of (Si, P)(O, N)4 tetrahedra. All tetrahedra comprise substitutional disorder which is why we refer to it as the fundamental disorder unit (FDU). We classified four different FDU motifs, revealing systematic bonding patterns. Including literature known Sr5Si2P6N16, three of the four patterns were found in the presented compounds. Common techniques like single‐crystal X‐ray diffraction (SCXRD), elemental analyses, and 31P nuclear magnetic resonance (NMR) spectroscopy were utilized for structural analysis. Additionally, low‐cost crystallographic calculations (LCC) provided insights into the structure of Sr16Si9P9O7N33 where NMR data were unavailable due to the lack of bulk samples. The optical properties of these compounds, when doped with Eu2+, were investigated using photoluminescence excitation (PLE), photoluminescence (PL) measurements, and density functional theory (DFT) calculations. Factors influencing the emission properties, including thermal quenching mechanisms, were discussed. This research reveals the new class of oxonitridosilicate phosphates with unique systematic structural features that offer potential for theoretical studies of luminescence and band gap tuning in insulators. [ABSTRACT FROM AUTHOR]

This study presents the synthesis and characterization of oxonitridosilicate phosphates Sr3SiP3O2N7, Sr5Si2P4ON12, and Sr16Si9P9O7N33 as the first of their kind. These compounds were synthesized under high‐temperature (1400 °C) and high‐pressure (3 GPa) conditions. A unique structural feature is their common fundamental building unit, a vierer single chain of (Si, P)(O, N)4 tetrahedra. All tetrahedra comprise substitutional disorder which is why we refer to it as the fundamental disorder unit (FDU). We classified four different FDU motifs, revealing systematic bonding patterns. Including literature known Sr5Si2P6N16, three of the four patterns were found in the presented compounds. Common techniques like single‐crystal X‐ray diffraction (SCXRD), elemental analyses, and 31P nuclear magnetic resonance (NMR) spectroscopy were utilized for structural analysis. Additionally, low‐cost crystallographic calculations (LCC) provided insights into the structure of Sr16Si9P9O7N33 where NMR data were unavailable due to the lack of bulk samples. The optical properties of these compounds, when doped with Eu2+, were investigated using photoluminescence excitation (PLE), photoluminescence (PL) measurements, and density functional theory (DFT) calculations. Factors influencing the emission properties, including thermal quenching mechanisms, were discussed. This research reveals the new class of oxonitridosilicate phosphates with unique systematic structural features that offer potential for theoretical studies of luminescence and band gap tuning in insulators. [ABSTRACT FROM AUTHOR]

Two novel metal borates, namely, Ag7B9O16(OH)2 (1) and AgCa2B7O11(OH)4 (2) were obtained under hydrothermal conditions. Ag7B9O16(OH)2 crystallizes into the centrosymmetric space group of C2/c in the monoclinic crystal system and displays a unique three‐dimensional (3D) framework built by 1D double borate chains further connected by Ag cations. AgCa2B7O11(OH)4 also belongs to monoclinic space group C2/c and it features borate chains with B8O8 8‐membered rings along the c axis which are further coordinated via AgO3 into 2D layers. These layers are bridged via CaO8 polyhedron into the final 3D framework. Two compounds were further characterized through thermogravimetric and optical analysis and density functional theory calculation have also been carried out, addressing their electronic structures. [ABSTRACT FROM AUTHOR]

In this work, we study the impact of the external electric field (E ext ) on graphene oxide (GO) layer to improve and optimize its electronic and optical properties, as a result to enhance optoelectronic device technology applications. A three-dimensional E ext applied on GO will be examined using the density functional theory (DFT). The E ext causes significant modifications to the electronic and optical properties of GO. When increasing the E ext , a global increase is noted in the bandgap in the x- and y-directions. As for the z-direction, the bandgap energy of GO decreases for an increasing E ext . The absorption coefficient (α) peaks intensities decreased in both visible and ultraviolet (UV) ranges by the effect of the E ext applied in the x-direction, and were increased when the E ext is applied in the y- and z-directions. It was found that, the electronic and optical properties of GO material, could be controlled by the effects of the E ext and by its direction. [ABSTRACT FROM AUTHOR]

Based on density functional theory (DFT), the structural and physical properties of NaCaZ (Z = N, P, As) half-Heusler (HH) semiconductor materials have been studied under pressure up to 20 GPa. The ground state results show that the NaCaZ are chemically stable in α -phase structure and exhibit semiconducting behavior with an indirect bandgap. The optical parameters like the real and imaginary components of complex dielectric function, the absorption coefficient and refractive index are investigated and discussed. The obtained results show that NaCaZ have low value of reflectivity and high absorption coefficient in low ultraviolet and visible regions and exhibit small changes under pressure. Pressure-based elastic constants and their derivative parameters show that NaCaZ are mechanically stable and have brittle nature. Above 10 GPa, NaCaP and NaCaAs have ductile nature. The phonon dispersions calculations with pressure show that NaCaN and NaCaP are dynamically stable, in contrast, NaCaAs is dynamically unstable at ambient pressure. Above 10 GPa, the studied compounds are dynamically stable. The mechanically, dynamically stable with low reflectivity and high absorption coefficient in the low ultraviolet and visible regions make these materials more promising as absorbers of solar cells, optoelectronic and 2D applications. [ABSTRACT FROM AUTHOR]

The double perovskites have excellent photocatalytic capabilities and could be used for water splitting purposes. Herein, we used density functional theory (DFT) computations to inspect the compound's characteristics. Generalized gradient approximation (GGA)-Perdew-Burke-Ernzerhof (PBE) exchange-correlation functional with compounds space group 123 (p4/mmm) are used for investigations. According to the findings, The structural characteristics show that these compounds have a tetragonal nature (a = b≠c) with 16 atoms. The electronic band structures indicate that all compounds have a semiconductor nature with an indirect energy bandgap E g of 2.25 eV, 2.92 eV, and 2.31 eV for RbCa 2 Ti 3 O 10 , RbMg 2 Zr 3 O 10 , and RbMg 2 Ti 3 O 10 , respectively. According to analyses of the Mulliken atomic (MA) populations, every chemical has complex bonding with both covalent and ionic characteristics. The elastic characteristics of the perovskite revealed that it is elastically anisotropic and mechanically stable. The calculated values of Pugh's (1.48, 1.91, 4.42) and Poisson's (0.22, 0.28, 0.39) ratios indicate that the substances RbCa 2 Ti 3 O 10 and RbMg 2 (Zr/Ti) 3 O 10 under study are brittle and ductile by nature. As a result, we anticipate that these compounds are valuable in the growth of high-performance photocatalytic devices for water splitting for various applications like producing hydrogen and oxygen. • All compounds display semiconductor characteristics with an indirect energy bandgap (Eg). • Mulliken atomic (MA) population analyses reveal complex bonding with both covalent and ionic characteristics. • The perovskite is elastically anisotropic and mechanically stable. • Pugh's ratios and Poisson's ratios suggest that RbCa2Ti3O10 and RbMg2(Zr/Ti)3O10 are brittle and ductile by nature. • These compounds can contribute to the development of high-performance photocatalytic devices for water splitting. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Controlled synthesis of lead‐halide perovskite crystals is challenging yet attractive because of the pivotal role played by the crystal structure and growth conditions in regulating their properties. This study introduces data‐driven strategies for the controlled synthesis of oriented quasi‐spherical CsPbBr3, alongside an investigation into the synthesis mechanism. High‐throughput rapid characterization of absorption spectra and color under ultraviolet illumination was conducted using 23 possible ligands for the synthesis of CsPbBr3 crystals. The links between the absorption spectra slope (difference in the absorbance at 400 nm and 450 nm divided by a wavelength interval of 50 nm) and crystal size were determined through statistical analysis of more than 100 related publications. Big data analysis and machine learning were employed to investigate a total of 688 absorption spectra and 652 color values, revealing correlations between synthesis parameters and properties. Ex situ characterization confirmed successful synthesis of oriented quasi‐spherical CsPbBr3 perovskites using polyvinylpyrrolidone and Acacia. Density functional theory calculations highlighted strong adsorption of Acacia on the (110) facet of CsPbBr3. Optical properties of the oriented quasi‐spherical perovskites prepared with these data‐driven strategies were significantly improved. This study demonstrates that data‐driven controlled synthesis facilitates morphology‐controlled perovskites with excellent optical properties. [ABSTRACT FROM AUTHOR]

Two-dimensional (2D) MXenes, having comparable transport properties like graphene and a wide spectrum application, are often limited to being used in optoelectronics due to metallic bandgap. Here, by employing density functional theory we report the bandgap engineering and tuning optoelectronic properties through modulating the anions of novel 2D spinel Hf3X2O2 (X = N, P and As) MXenes structures and show that the material class can be among the few semiconducting MXenes. Phonon spectra and cohesive energies confirm that these structures are dynamically stable and chemically exothermic. Modulating anions X = N, P, and As in Hf3X2O2, the electronic bandgaps are found ∼0.46 eV for N, metallic for P, and ∼48 meV for As atoms, suggesting the semiconducting, metallic, and semi-metallic MXenes. The biaxial strains are incorporated to tune the features: In the Hf3N2O2 structure, the bandgap is increased with both compressive and tensile strains, while for the Hf3As2O2 structure, the gap decreased at the GGA-PBE level. For Hf3P2O2 structures, the bandgaps are all metallic irrespective of pristine or biaxial strain. Spin–orbit coupling SOC+GGA reveals that Hf3N2O2 is highly spin responsive while Hf3As2O2 shows semi-metal-to-metallic bandgap transition for pristine as well as biaxial strained conditions. From optical properties analysis, optical absorptions are found located in the visible spectral regions that are also highly receptive to biaxial strains. These properties we have unleashed for the novel Hf3X2O2 (X = N, P, As) semiconducting MXene, thus, show the potentiality of the utilization of the material class in nanoelectronics and optoelectronics applications. [ABSTRACT FROM AUTHOR]

This study presents a thorough theoretical investigation into the intrinsic properties of Sr2RuO4 material that has garnered significant attention due to its half-metallic nature. Utilizing advanced Density Functional Theory (DFT) simulations, the examination of the electronic, optical, and thermoelectric properties provides insights into the fundamental behaviors of Sr2RuO4. The DFT simulations reveal critical aspects of its electronic structure, which supports the material's potential application in spintronic devices. Additionally, the optical properties are analyzed. The study extends to evaluating the thermoelectric performance, suggesting avenues for energy conversion efficiency. To complement these analyses, the Gibbs2 method is employed to assess the thermodynamic stability and responses of Sr2RuO4, offering predictions on its thermal behavior under various conditions. The convergence of these theoretical predictions provides a foundational understanding of Sr2RuO4, paving the way for its application in future technologies. [ABSTRACT FROM AUTHOR]

Adsorption of small Te clusters on tellurene and M o S 2 monolayers have been studied within density functional framework. With adsorption on 2D monolayers, Te clusters show distortion in cluster geometry along with local distortions in the monolayer. Adsorption energy is found to be higher in T e n $ t e l l u r e n e as compared to T e n $ M o S 2 , suggesting that there exists a strong interaction between Te clusters and tellurene substrate. Adsorption of clusters on monolayers results in the modification of the effective band gap of these monolayers. Analysis of the charge density difference profile shows that a certain amount of charge is transferred from the clusters to the substrates. This results in the redistribution of the charge. Our optical calculations for the interband transitions show that Te cluster creates quantum states inside of monolayers, which leads to increasing optical absorption of the system. Additional low-intensity absorption peak, in addition to the main peak, has been noticed in cluster-adsorbed M o S 2 monolayer for E ‖ C. The real part of the dielectric function reveals the existence of plasmon frequencies. We conclude that the cluster adsorption on different monolayers alters the electronic and dielectric properties of monolayers. [ABSTRACT FROM AUTHOR]

In this work, we comparatively studied the electronic and optical properties of triangular-shaped nanoflakes of VX 2 with varying flake sizes and compositions. We calculated the electronic properties using the density functional theory (DFT) while employing the time-dependent density functional theory (TD-DFT) to explore the optical properties of nanoflakes. The density of states (DOS) of VX 2 triangular nanoflakes showed the existence of localized metallic states, primarily originating from the presence of edge atoms in the flake. The optical spectra of VX 2 triangular nanoflakes revealed that the discrete peaks at low energy levels show broadening as flake size increases while splitting in resonance peaks upon changing the composition of the nanoflake. To gain insights into the nature of photoabsorption peaks, we analyzed the induced density and transition contribution map (TCM), which revealed the presence of both single-particle excitations and collective excitations. The collective excitations are known as plasmons which arise from the localized metallic edge states of the nanoflakes. This study sheds light on how nanoflakes' electronic and optical characteristics depend heavily on their shape, size, and composition. Future experiments are necessary to validate these theoretical findings. [ABSTRACT FROM AUTHOR]

We present a comprehensive study of transport coefficients including DC electrical conductivity and related optical properties, electrical contribution to the thermal conductivity, and the shear viscosity via ab initio molecular dynamics and density functional theory calculations on the "priority 1" cases from the "Second Charged-Particle Transport Coefficient Workshop" [Stanek et al., Phys. Plasmas (to be published 2024)]. The purpose of this work is to carefully document the entire workflow used to generate our reported transport coefficients, up to and including our definitions of finite size and statistical convergence, extrapolation techniques, and choice of thermodynamic ensembles. In pursuit of accurate optical properties, we also present a novel, simple, and highly accurate algorithm for evaluating the Kramers–Kronig relations. These heuristics are often not discussed in the literature, and it is hoped that this work will facilitate the reproducibility of our data. [ABSTRACT FROM AUTHOR]

This article employed a first-principles calculation method based on density functional theory to optimize the geometric structure of the ternary layered nitride M2 AlN (M = Ti, Zr). The structural, mechanical, electronic and optical properties of the ternary layered nitride M2 AlN (M = Ti, Zr) under high pressure were investigated. The study of structural and mechanical properties reveal that Ti2 AlN exhibits superior compressibility compared to Zr2 AlN. The elastic constants further validate its mechanical stability under high pressure. Ductility and elastic anisotropy enhance under increasing pressure, with Zr2 AlN demonstrating heightened sensitivity to these pressure conditions. Research on electronic properties reveals that both ternary layered nitrides exhibit metallic behavior, and their covalent character strengthen with increasing pressure. Investigations into the optical properties reveal that the polycrystalline nature and static dielectric functions ε1 (0), along with the static refractive index n(0) of Ti2 AlN and Zr2 AlN along various axes, demonstrate relatively low anisotropy in their optical characteristics. Both ternary nitrides exhibit pronounced capabilities for light absorption and reflectivity. Theoretical inquiries in this study clarified the relevant characteristics of the ternary layered nitrides Ti2 AlN and Zr2 AlN under the elevated pressure, establishing a robust theoretical framework for subsequent experimental investigations. [ABSTRACT FROM AUTHOR]

The computational study of the van der Waals hetero (vdW) bilayer GeI2/InTe has been carried out in present study. The isolated monolayer GeI2 and InTe have been studied first and the results were compared to the previous studies. The possible stackings are considered after the vdW interaction correction is applied in the structure relaxation. The vdW hetero bilayer stability has been checked from the phonon dispersion and ab initio Molecular Dynamics calculations. The charge transfer from InTe to GeI2 monolayer. Type-II indirect band gap (1.98, 2.01 eV) is verified by the projected band structure and band alignment calculations. The vdW hetero bilayer is a superior photocatalyst for the pH value up to pH = 0 to 11. The optical properties are calculated from the complex dielectric constant. The absorption coefficient shows the enhance absorption of light in the visible and ultraviolet regions. The vdW hetero bilayer has shown low reflectivity (37%) and a high refractive index (2.80) in the visible region. The enhanced optical properties have shown its possible applications in optoelectronic devices. [ABSTRACT FROM AUTHOR]

We utilize density functional theory to explore dicarbonitrile‐polyphenyl networks overlaid on graphene as a method for manipulating the density of Li atoms in a specific assembly pattern. Ab initio molecular dynamics calculations affirm the thermal stability of the introduced systems. We scrutinized the electronic structure and optical properties of the resultant systems, illustrating a systematic modulation of optical characteristics. Our results suggest that the optical excitation frequencies of (Li‐dicarbonitrile‐polyphenyl)/G can be efficiently tuned by systematically adjusting the density of Li atoms on graphene. [ABSTRACT FROM AUTHOR]

This work elucidates the impact of strain on the optical and electronic properties of Fe-doped lithium niobate using density functional theory. The Fe-doped lithium niobate is applied with the tensile and compressive strain (10% and 20%) and optical properties are analyzed. Lithium niobate, a large bandgap material (bandgap 3.56 eV), has absorption limited to the UV region of the optical spectrum only. For the Fe-doped lithium niobate, the bandgap is 1.38 eV, with low absorption in the visible region. The computed results show that the tensile and compressive strains have significantly narrowed down the bandgap of Fe-doped lithium niobate in compression to the unstrained structures. The decrease in the bandgap is largest for the tensile strain of 20% among all the applied strains. Further, visible light absorption is also improved due to the application of strain. The improvement in visible light absorption is highest for the tensile strain of 20% with absorption completely shifted in the desired visible region. The improved visible absorption due to the applied strain makes Fe-doped lithium niobate a potential candidate for optoelectronics and solar applications. [ABSTRACT FROM AUTHOR]

2D metal phosphorus trichalcogenides (MgPX3) have attracted tremendous research interests in spintronic, electrocatalytic, and photoelectronic applications due to their unique magnetic and optical properties. Herein, a systematical investigation on the electronic structures and optical properties of 2D MgPX3 (X = S and Se) monolayers is performed by density functional theory. Owing to small cleavage energy, 2D MgPX3 monolayers can be obtained by mechanical exfoliation with an excellent structure stability of 2D MgPX3 monolayers demonstrated by elastic tensor, phonon dispersion, and molecular dynamics, respectively. 2D MgPX3 behaves as a direct bandgap semiconductor with a strong optical absorption in UV range whereas a weak adsorption near the band edge, demonstrated by both single‐ and quasiparticle approximations. Upon analyses on transition dipole moment along with the wave function symmetry, the weak optical absorption is attributed to the parity‐forbidden effect where the wave functions almost show the same parity between top valence band and bottom conduction band. The findings indicate that 2D MgPX3 monolayers hold promise as candidate materials for flexible UV photoelectronics devices and provide a theoretical insight into the optical properties of 2D semiconductors. [ABSTRACT FROM AUTHOR]

Density functional theory based on projector‐augmented wave methodology is employed to conduct an in‐depth investigation into the structural, optical, and electrical properties of pristine PdSe2 and Pt‐doped PdSe2 monolayers. The computational framework uses the Perdew–Burke–Ernzerhof functional within the generalized gradient approximation. Evaluation of the calculated formation energy (Eform) and binding energy (Eb) demonstrates the thermodynamic favorability of Se vacancy on PdSe2 and the formation of a strong PtPdSe2 bond. The intrinsic indirect bandgap of PdSe2 (1.2 eV) undergoes a transition to a direct bandgap (0.71 eV) following Pt doping. In the context of optoelectronic applications, the investigation of optical properties reveals an elevated dielectric constant of 4.6 and 1.9 in the XX and ZZ planes for Pt‐doped PdSe2. Enhanced optical absorption is observed at ≈6.8 and 10.7 eV in the XX and ZZ planes, respectively. A notable redshift in the absorption coefficient and reflectivity constitutes significant findings. These results underscore the potential of tailoring PdSe2 optical and electrical properties, offering promising avenues for applications, particularly in the domain of nanoelectronics and optoelectronics devices. [ABSTRACT FROM AUTHOR]

In the quest for advanced materials with diverse applications in optoelectronics and energy storage, we delve into the fascinating world of halide perovskites, focusing on SiAuF3 and SiCuF3. Employing density functional theory (DFT) as our guiding light, we conduct a comprehensive comparative study of these two compounds, unearthing their unique structural, electronic, elastic, and optical attributes. Structurally, SiAuF3 and SiCuF3 reveal their cubic nature, with SiCuF3 demonstrating superior stability and a higher bulk modulus. Electronic investigations shed light on their metallic behavior, with Fermi energy levels marking the boundary between valence and conduction bands. The band structures and density of states provide deeper insights into the contributions of electronic states in both compounds. Elastic properties unveil the mechanical stability of these materials, with SiCuF3 exhibiting increased anisotropy compared to SiAuF3. Our analysis of optical properties unravels distinct characteristics. SiCuF3 boasts a higher refractive index at lower energies, indicating enhanced transparency in specific ranges, while SiAuF3 exhibits heightened reflectivity in select energy intervals. Further, both compounds exhibit remarkable absorption coefficients, showcasing their ability to absorb light at defined energy thresholds. The energy loss function (ELF) analysis uncovers differential absorption behavior, with SiAuF3 absorbing maximum energy at 6.9 eV and SiCuF3 at 7.2 eV. Our study not only enriches the fundamental understanding of SiAuF3 and SiCuF3 but also illuminates their potential in optoelectronic applications. These findings open doors to innovative technologies harnessing the distinctive qualities of these halide perovskite materials. As researchers seek materials that push the boundaries of optoelectronics and energy storage, SiAuF3 and SiCuF3 stand out as promising candidates, ready to shape the future of these fields. [ABSTRACT FROM AUTHOR]

The energy crisis can be met by switching to renewable energy sources. The present study explores the physical and hydrogen storage capacity of XCdH 3 (X = K, Rb) by first-principles study. According to the phonon spectrum and formation, energy materials are dynamically stable. The electronic profile revealed that the concerned compounds are half-metallic. Furthermore, the electronic band gap is evaluated in terms of the total and partial density of states. In terms of hypothetical dielectric function optical properties are discussed and in the energy range of 0–40 eV. In optical properties, the highest reflectivity and absorption are observed in KCdH 3. Mechanically, KCdH 3 shows brittle properties and RbCdH 3 has ductile properties. Lattice constant, elastic coefficient, Poisson ratio anisotropy, Young, and shear modulus, are calculated. The gravimetric hydrogen storage is found 5.55 %, and 4.32 % wt% of KCdH 3 and RbCdH 3 , respectively. KCdH 3 qualified as the best substance for storing hydrogen due to the greater gravimetric ratio. All the above parameters are calculated the first time. Evaluation of concerned material provides a roadmap and significant contribution to scientific literature for future prospective. • Doping of potassium and rubidium XCdH 3 (X = K, Rb) to improve the efficiency of hydrogen storage. • Effect of alkali metals enhance the visible-light absorption of XCdH 3 (X = K, Rb). • The low recombination rate and charge carrier transportation supported to improve the efficiency of hydrogen capacity. • Novelty base materials are dynamically stable and synthesizable. [ABSTRACT FROM AUTHOR]

With the reported synthesis of a fully planar 2D silicon carbide (SiC) allotrope, the possibilities of its technological applications are enormous. Recently, several authors have computationally studied the structures and electronic properties of a variety of novel infinite periodic SiC monolayers, in addition to the honeycomb one. In this work, we perform a systematic first-principles investigation of the geometry, electronic structure, vibrational, and optical absorption spectra of several finite, but, fully planar structures of SiC, i.e. 0D quantum dots (QDs). The sizes of the studied structures are in the 1.20–2.28 nm range, with their computed HOMO(H)-LUMO(L) gaps ranging from 0.66 eV to 4.09 eV, i.e. from the IR to the UV region of the spectrum. The H-L gaps in the SiC QDs are larger as compared to the band gaps of the corresponding monolayers, confirming the quantum confinement effects. In spite of covalent bonding in the QDs, Mulliken charge analysis reveals that Si atoms exhibit positive charges, whereas the C atoms acquire negative charges, due to the different electron affinities of the two atoms. Furthermore, a strong structure property relationship is observed with fingerprints both in the vibrational and optical spectra. The wide range of H-L gaps in different SiC QDs makes them well-suited for applications in fields such as photocatalysis, light-emitting diodes, and solar cells. [ABSTRACT FROM AUTHOR]