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Molecular and crystal structures of the novel [Pd{(PhO)2PS2}2] complex and the known [Pd{(EtO)2PS2}2] complex are studied. According to the XRD data, [Pd{(RO)2PS2}2] (R = Et, Ph) compounds crystallize in centrosymmetric space groups, and their crystal structures consist of mononuclear complex molecules. The and ions perform an S,S′-donor bidentate-chelating function leading to the formation of square-planar PdS4 coordination cores. The electronic absorption spectra of the solutions of these complexes are studied; the influence of the ligand structure and the solvent polarity on the observed optical properties of the studied compounds is considered. [ABSTRACT FROM AUTHOR]

In this paper, we study the effects of different doping concentrations of O, Se, and Te atoms on the electronic structure and optical properties of single layer WS2 based on the density generalization theory of the first principles. The most stable structure. The system doped with Te atoms shows a shift from direct to indirect band gap, and the band gap of the system doped with Se atoms increases slightly. When investigating the optical properties, we also found that the absorption of light in each doped system mostly occurs in the ultraviolet region, and the absorption of light in the system doped with O atoms decreases, while the absorption of light in the system doped with Se and Te atoms changes with different frequencies. The reflectivity is higher than the intrinsic state. [ABSTRACT FROM AUTHOR]

In this paper, we study the effects of different doping concentrations of O, Se, and Te atoms on the electronic structure and optical properties of single layer WS2 based on the density generalization theory of the first principles. The most stable structure. The system doped with Te atoms shows a shift from direct to indirect band gap, and the band gap of the system doped with Se atoms increases slightly. When investigating the optical properties, we also found that the absorption of light in each doped system mostly occurs in the ultraviolet region, and the absorption of light in the system doped with O atoms decreases, while the absorption of light in the system doped with Se and Te atoms changes with different frequencies. The reflectivity is higher than the intrinsic state. [ABSTRACT FROM AUTHOR]

Bostrycoidin is one of the pigments produced by the Fusarium genus of fungi. On the one hand, it has significant pharmacological importance, while on the other hand, it serves as a presence marker of Fusarium infection in useful grain crops, fruits, and soils. In this regard, the structural and optical properties of the bostrycoidin molecule were studied in the framework of density functional theory (DFT). The most stable geometry as well as higher-energy conformers and tautomers were investigated. The lowest-energy tautomer was found to be about 3 kcal/mol higher in energy than the most stable structure, resulting in relatively low population of this state. The obtained conformational rotamers associated with the rotation of the OMe group possess similar energy. The vibrational spectrum was modeled for the most stable conformer, and the most active peaks in the IR absorbance spectrum were assigned. Moreover, the electronic absorption spectrum was simulated within the time-dependent DFT approach. The obtained theoretical spectrum is in good agreement with the experimental data and the theoretically calculated longest-wavelength transition (HOMO–LUMO) was about 498 nm. [ABSTRACT FROM AUTHOR]

New Y-shaped ferrocene (Fc)-conjugated trifluoromethyl-substituted imidazole (IM) donor–π–acceptor [(D–π)2–IM–D′–π–CF3] "push–pull" chromophores [(Fc–CH＝CH)2–IM–C6H4–R–C6H4–CF3] {R= –OCH3 (1); –N(C2H5)2 (2)} were synthesized and structurally characterized. The structure of the chromophores was confirmed via single-crystal X-ray diffraction studies. They crystallized in the triclinic P1¯ (for 1) and monoclinic P21/c (for 2) space groups. Thermogravimetric analysis (TGA) was used to study the thermal stability of chromophores 1 and 2, and it was found that both were stable at temperatures of about 300 °C. The redox properties were studied through cyclic voltammetry (CV), which revealed one-electron transfer from the ferrocene to ferrocenium ion (Fe2+ Fe3+), and their potentials were utilized to calculate their energy gaps, which were 2.16 eV for 1 and 2.12 eV for 2. The second-order nonlinear optical (NLO) properties of chromophores 1 and 2 were explored via electric-field-induced second-harmonic generation (EFISH) technique in CHCl3 solution with an incident wavelength of 1907 nm. μβEFISH values were −725 × 10−48 esu and −806 × 10−48 esu for 1 and 2, respectively. The μβEFISH values slightly decreased compared with other reported ferrocene-conjugated Y-shaped imidazole chromophores owing to their substitution on imidazole nitrogen, which increases steric hindrance and reduces the ICT process in the chromophores. In addition, their frontier molecular orbital levels, excited and ground state dipole moments (μe and μg), and electronic absorption spectra were studied using density functional theory (DFT) and time-dependent density functional theory (TD-DFT) with the B3LYP method using the 6-31+G** basis set. [ABSTRACT FROM AUTHOR]

Nanographenes are of increasing importance owing to their potential applications in the photoelectronic field. Meanwhile, recent studies have primarily focused on the pure electronic spectra of nanographenes, which have been found to be inadequate for describing the experimental spectra that contain vibronic progressions. In this study, we focused on the vibronic effect on the electronic transition of a range of chiral nanographenes, especially in the low-energy regions with distinct vibronic progressions, using theoretical calculations. All the calculations were performed at the PBE0-D3(BJ)/def2-TZVP level of theory, adopting both time-dependent and time-independent approaches with Franck–Condon approximation. The resulting calculated curves exhibited good alignment with the experimental data. Notably, for the nanographenes incorporating helicene units, owing to the increasing π-extension, the major vibronic modes in the vibrationally resolved spectra differed significantly from those of the primitive helicenes. This investigation suggests that calculations that account for the vibronic effect could have better reproducibility compared with calculations based solely on pure electronic transitions. We anticipate that this study could pave the way for further investigations into optical and chiroptical properties, with a deeper understanding of the vibronic effect, thereby providing theoretical explanations with higher precision on more sophisticated nanographenes. [ABSTRACT FROM AUTHOR]

The structural, electronic, and optical properties of nine different polymorphs of silica are investigated with both the traditional generalized gradient approximation (GGA) scheme and the hybrid functional. These include the 4:2-coordinated systems of quartz, tridymite, cristobalite, coesite, and keatite, as well as the 6:3-coordinated stishovite. The phases with similar crystal structures tend to share analogous electronic and optical features, while these properties are different in the case of stishovite. For the 4:2-coordinated polymorphs, linear relations are firmly established between the bandgap and the static dielectric constant vs the unit cell volume, respectively. Further investigation of their refractive indices also reveals a strong linearity with the corresponding densities. Our calculation with the sX functional reproduces the experimental bandgap values well, while GGA is superior for the overall trends of their optical properties. [ABSTRACT FROM AUTHOR]

Pentagonal two-dimensional (2D) materials, distinguished by their unique pentagonal atomic configurations, have emerged as a new class of materials with remarkable physical and chemical properties. In this work, we investigate the effect of an external electric field and biaxial strain on the electronic and optical properties of two-dimensional Pentagonal PtX 2 (X= S, Se, Te) monolayers denoted by Penta-PtX 2 using the first-principles calculations. We found that Penta-PtX 2 monolayers are semiconductors with an indirect band gap of 1.92 eV, 1.51 eV, and 1.4 eV for Penta-PtS 2 , Penta-PtSe 2 , and Penta-PtTe 2 , respectively, that is larger than the 1T phase. External electric fields cause a slight decrease in the band gap of Penta-PtX 2 monolayers without changing the main feature of the electronic band structures. Tensile biaxial strain causes a continuous decrease in the band gap up to 12 % while compressive biaxial strain increases the band gap at first then it starts to decrease. However, phonon dispersion calculations showed that Penta-Ptx 2 are stable under tensile strain up to 12 % while they are unstable under compressive strain. The investigation of the optical properties revealed that monolayers Penta-PtX 2 have in-plane anisotropic optical properties with higher absorption spectra occurring along the y-direction for strained and unstrained structures. The maximum absorption occurs in the Ultraviolet (UV) region, therefore, they can harvest UV and visible photons more effectively. In contrast, the reflectivity is higher along the x-direction for both strained and unstrained monolayers where the maximum reflectivity occurs in the Infrared (IR) region. The combination of anisotropic properties and the unique characteristics of Pentagonal symmetry make Penta-PtX 2 monolayers attractive for fundamental scientific studies to better understand their behavior. They hold great promise for developing new technologies in the fields of optoelectronics and nanotechnology, potentially leading to innovative devices and applications. [ABSTRACT FROM AUTHOR]

This study was planned to prepare new mixed ligand chelates derived from N‐(4,6‐dimethylpyrimidin‐2‐yl)‐3a,4,5,6,7,7a‐hexahydro‐1H‐benzimidazol‐2‐amine (BIP), and imidazole (I). They identified through CHN study, spectroscopic (NMR, FT‐IR, and UV–Vis), conductivity, magnetic susceptibility, mass analysis, and thermal analysis. Correlation between all results exposed that the BIP ligand performed as a bi‐dentate ligand through NN donation locations, where the co‐ligand shows as N–H monodentate. The optimization for the studied chelates led to the formation of distorted octahedral geometry for BIPICu and BIPIVO chelates, distorted (tetrahedral and square planar) geometry for BIPIAg and BIPIPd chelates, respectively, around the metal salt. The B3LYP level, B3LYP/6‐311G** level for the free ligand, and B3LYP/6–311G**‐LANL2DZ functional level for the solid chelates were used in density functional theory (DFT) calculations. The findings showed that DFT calculations produce conclusions that are consistent with those of the experiments. The resulting compounds' nonlinear optical properties were examined by calculating the hyperpolarizability (β) and molecular polarizability (α) parameters, which gave rise to several unexpected optical properties for the synthesized compounds. Using the agar well diffusion method, the antimicrobial activity of the produced compounds was experimentally confirmed against a subset of G+ and G− bacteria. To ascertain how these substances attach to the targeted protein binding sites, a molecular docking mechanism between the microbially resistant chelates and their suppressed microbial protein pocket receptors was investigated. Also, DNA binding estimated for studied structures was tested by electronic absorption spectrum, viscosity estimation, and gel electrophoresis. Data proposed that all tested compounds link with DNA using an intercalation, electrostatic, and covalent binding mechanism. Moreover, antioxidant performance for studied compounds was governed by radical scavenging techniques in vitro. In addition, an MTT assay has been worked out to explore in vitro cytotoxic impending. All the tested chelates assumed antimicrobial, antitumor, and antioxidant performances that cause them to suggest drugs. [ABSTRACT FROM AUTHOR]

We present a highly efficient method for the extraction of optical properties of very large molecules via the Bethe–Salpeter equation. The crutch of this approach is the calculation of the action of the effective Coulombic interaction, W, through a stochastic time-dependent Hartree propagation, which uses only ten stochastic orbitals rather than propagating the full sea of occupied states. This leads to a scaling that is at most cubic in system size with trivial parallelization of the calculation. We apply this new method to calculate the spectra and electronic density of the dominant excitons of a carbon-nanohoop bound fullerene system with 520 electrons using less than 4000 core hours. [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]

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: 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]

β-Ga2O3 with an ultra-wide bandgap demonstrates great promise in applications of space missions as power electronics and solar-blind photodetector. Unraveling the radiation damage effects on its material properties is of crucial importance, especially for improving the radiation tolerance of Ga2O3-based devices. Herein, we evaluate the formation energy of gallium and oxygen vacancy defects and comprehensively investigate their influence on the electronic and optical properties of β-Ga2O3 using first-principles calculations. Ga vacancies act as deep acceptors and produce p-type defects in β-Ga2O3, while the defective Ga2O3 with O vacancies exhibits the n-type characteristics. A semimetal characteristic is observed in the defective Ga2O3 with Ga vacancies, and an apparent optical absorption peak in the infrared spectral range emerges. Moreover, the self-compensation effect emerges when β-Ga2O3 contains both Ga vacancies and O vacancies, leading to the reduced absorption peak. The doping effect on the defect formation energy of β-Ga2O3 is also investigated, and Ga vacancies are found to be easily formed in the case of In doped β-Ga2O3 (InGa2O3) compared to the undoped β-Ga2O3, while O vacancies are much harder to form. This work provides insights into how gallium and oxygen vacancy defects alter electronic and optical properties of β-Ga2O3, seeking to strengthen its radiation tolerance. [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]

First-principles calculations have been performed on (HfO 2) p and Hf q Zr r O 2 (q + r) clusters using DFT and TDDFT. The effect of Zr-substitution on the structural, electronic, thermodynamic, and optical properties of (HfO 2) p clusters has been investigated using B3LYP and B3PW91 functionals with LANL2DZ basis set. The calculated properties depend upon geometry, type, and number of atoms present in the clusters. Zr-substitution in (HfO 2) p clusters leads to the reduced molecular mass of Hf q Zr r O 2 (q + r) clusters so that they can be used in making light weight semiconductor devices. Hf 3 Zr 2 O 10 is found to be the most reactive after Zr-substitution in (HfO 2) 5 because of the minimum value of HOMO-LUMO gap. Zr-substitution in (HfO 2) 5 increases the refractive index of Hf 3 Zr 2 O 10 , making it suitable for multi-layer antireflecting coatings. The dielectric constant of Hf 3 Zr 2 O 10 has increased after Zr-substitution finding applications in the MOSFET industry. The absorption spectra can be tuned over the ultraviolet and visible regions depending upon the Zr-substitution. [ABSTRACT FROM AUTHOR]

The present study explores an environmentally friendly green approach to obtain cerium oxide nanoparticles via a biomediated route using Mellisa officinalis and Hypericum perforatum plant extracts as reducing agents. The as-prepared nanoparticles were studied for their structural and morphological characteristics using XRD diffractometry, scanning electron microscopy, Raman, fluorescence and electronic absorption spectra, and X-ray photoelectron spectroscopy (XPS). The XRD pattern has shown the centered fluorite crystal structure of cerium oxide nanoparticles with average crystallite size below 10 nm. These observations were in agreement with the STEM data. The cubic fluorite structure of the cerium oxide nanoparticles was confirmed by the vibrational mode around 462 cm−1 due to the Ce-08 unit. The optical band gap was estimated from UV-Vis reflectance spectra, which was found to decrease from 3.24 eV to 2.98 eV. A higher specific area was determined for the sample using M. officinalis aqueous extract. The EDX data indicated that only cerium and oxygen are present in the green synthesized nanoparticles. [ABSTRACT FROM AUTHOR]

A semi organic crystalline salt - 1,3-diammonium propylarsenate (1-3-DAPSM) has been taken as the subject of theoretical investigation for its optical and nonlinear optical studies. Gaussian 09 program has been utilized to quantify the quantum chemical theoretical estimations with the aid of B3LYP exchange correlational function with 6-311++G(d,p) basis set. The electronic absorption spectra of the title compound have been recorded in the gas phase as well as in three different solvents, that is, ethanol, methanol, and water. Further frontier molecular orbital analysis has been done to identify the energy gap and charge transfer occurrence between the molecules. Further, the first-order hyperpolarizability (ß) of the 1,3-Diammonium Propylselenate Monohydrate molecule was computed to identify the nonlinear microscopic behavior of the studied compound. [ABSTRACT FROM AUTHOR]

Computational studies based on Density Functional Theory (DFT) and time-dependent DFT (TD-DFT) were used to determine molecular and thermodynamic parameters, optoelectronic and electronic properties, as well as chemical descriptors, UV–vis spectra and nonlinear optical response of the chromophores of 2-Styrylquinoline (M01) and 2-(3-nitrostyryl)quinoline (M02). We evaluated the impact of the substitution of the hydrogen atom in M01 by the nitro group (NO2) to obtain the molecule M02. The results show very good optoelectronic properties with respect to very high electric fields of the order of 1.43 × 109 Vm−1 for M01 up to 5.26 × 109 Vm−1 for M02. The energy gap decreases from 3.94 eV for M01 to 3.56 eV for M02; which suggest that they are semiconductors. In addition, these two molecules exhibit ionization potential (IP) and electron affinity (EA) quite close to those of Alq3 and could therefore be good candidates for the manufacture of Organic Light-Emitting Diodes (OLED). The chemical descriptors were assessed and allowed us to discuss the stability and reactivity of our molecules. Thus, the addition of the nitro group to the virgin 2-Styrylquinoline decreases the reactivity and stability of the 2-Styrylquinoline. The analysis of the IR and Raman vibrational spectra shows several peaks between 100 cm−1 and 3200 cm−1 of which the most intense for the molecule M01 are attributed to the stretching mode of the C–H bond in the phenyl ring and the C=C double bond in the quinoline ring. For the M02 molecule, stronger peaks were assigned to the stretching mode of the O–N and N–C bonds. The analysis of the UV–vis spectra showed that the maximum absorption wavelength of M01 is 334.80 nm and that of M02 is 375.37 nm; both located in the ultraviolet. The high values of first ( β T ) and second ( γ ¯ ) hyperpolarizability showed that both molecules have very good nonlinear optical properties and thus can be used for second and third harmonic generation. [ABSTRACT FROM AUTHOR]

In this study, we investigated, for the first time, the effects of the spatially varying effective mass, asymmetry parameter, and well width on the electronic and optical properties of a quantum well which has an improved Rosen–Morse potential. Calculations were made within the framework of the effective mass and parabolic band approximations. We have used the diagonalization method by choosing a wave function based on the trigonometric orthonormal functions to find eigenvalues and eigenfunctions of the electron confined within the improved Rosen–Morse potential. Our results show that the position dependence mass, asymmetry, and confinement parameters cause significant changes in the electronic and optical properties of the structure we focus on since these effects create a significant increase in electron energies and a blue shift in the absorption spectrum. The increase in energy levels enables the development of optoelectronic devices that can operate at wider wavelengths and absorb higher-energy photons. Through an appropriate choice of parameters, the Rosen–Morse potential offers, among many advantages, the possibility of simulating heterostructures close to surfaces exposed to air or vacuum, thus giving the possibility of substantially enriching the allowed optical transitions given the breaking of the system´s symmetries. Similarly, the one-dimensional Rosen–Morse potential model proposed here can be extended to one- and zero-dimensional structures such as core/shell quantum well wires and quantum dots. This offers potential advancements in fields such as optical communication, imaging technology, and solar cells. [ABSTRACT FROM AUTHOR]

It has become a priority of physics, chemistry, and material science to find new perovskite materials with environmentally friendly, excellent photoelectric properties and stable structures. This paper reports the design of lead-free double perovskite Rb2KBiCl6 and the effects of pressure on its structural, electronic, and optical properties. Also, its thermoelectric (TE) properties were systematically studied using a first-principles calculation based on density functional theory (DFT). It is found that Rb2KBiCl6 exhibits significant optical absorption in the ultraviolet range and that the band gap is an ideal choice for series photovoltaic applications and for use in wide-band-gap photovoltaic materials. At the same time, Rb2KBiCl6 shows excellent TE properties. In addition, the research results suggest a new way to adjust the crystal structure, optical band gap, and electronic structure of such materials. [ABSTRACT FROM AUTHOR]

It has become a priority of physics, chemistry, and material science to find new perovskite materials with environmentally friendly, excellent photoelectric properties and stable structures. This paper reports the design of lead-free double perovskite Rb2KBiCl6 and the effects of pressure on its structural, electronic, and optical properties. Also, its thermoelectric (TE) properties were systematically studied using a first-principles calculation based on density functional theory (DFT). It is found that Rb2KBiCl6 exhibits significant optical absorption in the ultraviolet range and that the band gap is an ideal choice for series photovoltaic applications and for use in wide-band-gap photovoltaic materials. At the same time, Rb2KBiCl6 shows excellent TE properties. In addition, the research results suggest a new way to adjust the crystal structure, optical band gap, and electronic structure of such materials. [ABSTRACT FROM AUTHOR]

Defects in two-dimensional (2D) transition metal dichalcogenides (TMDs) greatly influence their electronic and optical properties by introducing localized in-gap states. Using different non-invasive techniques, we have investigated the spatial distribution of intrinsic defects in as-grown chemical vapor deposition (CVD) MoS2 monolayers and correlated the results with the growth temperature of the sample. We have shown that by increasing the CVD growth temperature the concentration of defects decreases and their spatial distribution and type change, influencing the sample's electronic and optical properties. [ABSTRACT FROM AUTHOR]

In recent years, two-dimensional (2D) layered perovskites, have aroused considerable research interest due to their structural tunability and more stability compared to their 3D counterparts. The presence of long-chain organic cations strongly increases the stability of 2D perovskites. The electronic and optical properties of materials, as important parameters, can significantly affect the function of optoelectronic devices. In this paper, the electronic and optical properties of two-dimensional (2D) layered perovskite materials were studied due to their growing application in optoelectronic devices. The band structure, exciton binding energy, dielectric function, optical conductivity, absorption, and reflection spectra of a 2D (OCA) (MA)n−1 Pbn Br3n+1 (n = 1, 2, 3) perovskite with Dion–Jacobson structure compared with (BA)2 (MA)n−1 Pbn Br3n+1 (n = 1, 2, 3) with Ruddlesden–Popper structure were calculated by density functional theory (DFT) method. We observed that by increasing the number of inorganic sheets, n, the band gap, carrier effective mass, and exciton binding energy of both structures decrease and reach the value of 3D perovskite almost for n = 3 due to quantum confinement effects. The obtained results indicate that the 2D (OCA) with DJ structure has a suitable band gap, high exciton binding energy, and good high absorption in comparison to that of the 2D (BA) with RP structure. DFT calculations can help to get more insight into the experimental findings. These results can be implemented for designing and developing new 2D materials for optoelectronic devices. [ABSTRACT FROM AUTHOR]

Novel Zn(II) and Ni(II) complexes, [Zn(MeOPic)2(H2O)2] and [Ni(MeOPic)2(H2O)2] (MeOHPic = 4‐methoxypyridine‐2‐carboxylic acid [4meOHPic]), have been prepared and characterized by X‐ray diffraction (XRD), Fourier transform infrared (FTIR), and ultraviolet–visible (UV–Vis) techniques. Crystal structure analysis demonstrated that the 4meOHPic ligand is coordinated as a two‐dentate ligand through N and O atoms to central metal ions, and both of the complexes have distorted octahedral coordination geometry. The DFT‐B3LYP/6‐311++G(d,p)/LanL2DZ level was executed to perform DFT calculations for the Zn(II) complex with singlet spin state and the Ni(II) complex with triplet spin state. The UV–Vis electronic absorption spectra and natural bonding orbital (NBO) analyses also demonstrated that ligand–ligand and metal–ligand charge transfer interactions occur in Zn(II) and Ni(II) complexes. However, static and frequency‐dependent first‐order hyperpolarizability (β) parameters were found to be low because of the centrosymmetric crystal structures. As for the second‐order hyperpolarizabilities, the quadratic electro‐optical Kerr effect γ (−ω;ω,0,0) and electric field induced second harmonic generation γ (−2ω;ω,ω,0) parameters were calculated as 13.04 × 10−36 and 2258.9 × 10−36 esu for Ni(II) complex. Accordingly, it was demonstrated that Ni(II) complex is a potential candidate for third‐order nonlinear optical (NLO) materials. [ABSTRACT FROM AUTHOR]

This study addressed a theoretical and detailed investigation of the valence-band electronic and optical properties of a laser-dressed GaAsSb-based Rosen–Morse quantum well. The one-dimensional Schrödinger equation was solved by a developed BenDaniel and Duke approach considering a position-dependent effective mass for a heavy hole. The spatial dependence of the heavy hole effective mass was determined as a function of Rosen–Morse geometry of the quantum well. The electronic studies were achieved using the Finite-Element Method considering Kramers–Henneberger transformation along with the lines of the Floquet technique. The linear and the third-order nonlinear optical absorption coefficients and refractive index changes were calculated under the approximation of a two-level system using the density matrix method. Calculations were completed to examine the effects of externally applied intense laser and electric fields, well width, and the maximum antimony content. A transition was observed from a single Rosen–Morse confinement profile to a double-type one with doubly degenerated energy states and a red-shifted optical spectrum when the quantum well was irradiated by an intense laser field. Moreover, the axial symmetry and degeneracy were broken along with the emergence of a blue-shifted optical spectrum when the laser-dressed confinement profile was affected by an electric field. The results suggest a strong correlation between the optical and electronic findings through analyzing the energy differences and the dipole transition matrix elements. [ABSTRACT FROM AUTHOR]

In this paper, Fm-3m structure of HgF2 has been studied using the density functional theorem (DFT). The stability of this structure is revealed by the positive phonon frequencies of the phonon dispersion curves and by satisfying Born Huang criteria concerned with elasticity of the structure. For the very first time, the elastic constants C 1 1 , C 1 2 and C 4 4 of Fm-3m structure of HgF2 have been explored using thermo_pw package. The ductile nature of HgF2 is evidenced by its B ∕ G H ratio of 2.56. The linear response approach has been used to evaluate the intrinsic thermodynamic characteristics of HgF2 while examining the temperature fluctuations of the Helmholtz free energy (F) , internal energy (E) , specific heat at constant volume (Cv), and Debye temperature ( Θ D). The ionic behavior of HgF2 is demonstrated by the broad valence bandgap that is present in the electronic band structure and density of states. Moreover, the hybridization between "s", "p", and "d" orbitals in HgF2 is defined by the charge density along the [110] plane. The static refractive index of HgF2 is 1.26. The broad optical investigation demonstrates Fm-3m HgF2's transparency in the UV and visible spectrums. Additionally, it exhibits considerable UV absorption throughout its range as well as with absorption tail that continues into the visible spectrum. The overall optical parameters of Fm-3m HgF2 show non-linear optical behavior which makes the material to be useful in ultraviolet (UV) photo-sensing devices. [ABSTRACT FROM AUTHOR]

In recent years, three‐dimensional (3D) lead‐free double halide perovskites have been considered promising candidates for photovoltaic applications due to their high stability and the use of non‐toxic materials, and the absence of organic materials in their structure. The structural, electronic, and optical properties of 3D double Halide perovskites Cs2CuBiBr6 and Cs2CuBiCl6 were investigated in this paper using first‐principles density functional theory (DFT) simulation with BLYP approximation. The results showed that structures Cs2CuBiBr6 and Cs2CuBiCl6 have an indirect band gap, high absorption coefficient, low reflection, and high conductivity. A redshift of absorption edge and band gap shrinkage has been observed in the Cs2CuBiX6 structure with an increase in the ionic radius of the halogen, which indicates the unique features of structure Cs2CuBiBr6 for photovoltaic applications, LED, laser, and other optoelectronic devices. [ABSTRACT FROM AUTHOR]

A First-principles study was accomplish to examine the various characteristics of 2-D hetero-junction layer structure Molybdenum disulfide (MoS2) material such as structural, electronic, and optical properties through variation of external static pressure 0–100 GPa with a 4-steps escalations such as 0, 50, 75 100 GPa. Scheming bandgap tuning by the external static pressure engineering of 2-D layered MoS2 is a relatively new approach for tailoring different properties. The bandgap of MoS2 is found to be decreasing from 1.65 to 0.0 eV with increased external static pressure from 0 to 100 GPa. By increasing the external static pressure in MoS2 extra gamma states are produced into an energy band gap (Eg). The bandgap nature originated indirect moreover bandgap represented that material is an eminent semiconductor. MoS2 is a proficient photo-catalysis have a large surface area for light absorption and decreases the electron–hole pairs recombination rate and increases the charge transport. A significant decrement is found in the reflectivity due to the decrement in the bandgap. It is also examined that increment in energy adsorption peaks at 0 to 35 eV furthermore optical conductivity peaks shifts at larger energy band through increment the static pressure engineering. The optical properties significantly increased by the decrement of Eg. MoS2 has high energy absorption, optical conductivity, and refractive index and is an appropriate material for photocatalytic applications. [ABSTRACT FROM AUTHOR]

MXene is regarded as an innovative 2D nanomaterial for energy storage applications. In this study, we calculated the structural, electronic, optical, and mechanical properties of Ti3X2 (X = C, N, P, S) MXene materials using the CASTEP simulation package based on the density functional theory. The calculated lattice parameters at zero pressure are in good agreement with the previously reported results. We also calculate the studied materials' formation energy to check the compounds' stability. The negative formation energy values suggest that Ti3X2 (X = C, N, P, S) compounds are stable and can be synthesized experimentally. The electronic properties, i.e., electronic band structures, total density of state and partial density of state, suggest that Ti3X2 (X = C, N, P, S) compounds are metallic. To understand the behavior of light scattering, we calculate the optical properties of Ti3X2 (X = C, N, P, S). The maximum reflectivity occurs at 62%, 56%, 49%, and 33% for Ti3P2, Ti3C2, Ti3N2 and Ti3S2, respectively. Optical properties also suggest the metallic nature of studied materials. Mechanical properties suggest that Ti3C2 is ductile behavior and Ti3N2, Ti3P2, and Ti3S2 are brittle behavior. [ABSTRACT FROM AUTHOR]

Nanostructured metal sulfides such as copper sulfide (CUS) form from single-source precursors (SSPs) and are cost-friendly materials that can be used in a one-pot approach with potential applications in dye-sensitizer solar cells (DSCs). This is an attractive pathway that allows the careful control of tailoring the design of the nanostructures with slight variations in the mixture conditions to form uniform nanoparticles and enhance the performance of DSCs. We report on the optical, structural, and morphological properties of CuS as photosensitizers and their application in QDSCs using characterization techniques such as cyclic voltammetry (CV), current–voltage (I-V), UV-Vis spectroscopy (UV-Vis), X-ray diffraction (XRD), high-resolution transmission electron microscopy (HRTEM), etc. The UV-Vis reveals that the band gap for the three samples is found at 2.05–2.87 eV, confirming them as suitable materials for solar cells. The XRD peaks for the three CuS nanoparticles harmonized very well with hexagonal CuS. The thermal gravimetric (TGA) suitability of the three complexes shows a two-step decomposition within the temperature range of 125–716 °C, with a final residue of 2–4%. CV curves for three samples show that none of the developed metal sulfides exhibits a peak indicative of limited catalytic activity in the iodine electrolyte. The I-V overall energy conversion efficiency (η%) of 4.63% for the CuSb photosensitizer is linked to the wide electronic absorption spectrum and better relative dye loading. The synthesis of photosensitizers from a trioctylphosphine oxide (TOPO) capping agent shows improved efficiency compared to our previous studies, which used hexadecylamine as a coordinating solvent. [ABSTRACT FROM AUTHOR]

In recent years, transition metal dichalcogenides have received great attention since they can be prepared as two‐dimensional semiconductors, presenting heterodesmic structures incorporating strong in‐plane covalent bonds and weak out‐of‐plane interactions, with an easy cleavage/exfoliation in single or multiple layers. In this context, molybdenite, the mineralogical name of molybdenum disulfide, MoS2, has drawn much attention because of its very promising physical properties for optoelectronic applications, in particular a band gap that can be tailored with the material's thickness, optical absorption in the visible region and strong light–matter interactions due to the planar exciton confinement effect. Despite this wide interest and the numerous experimental and theoretical articles in the literature, these report on just one or two specific features of bulk and layered MoS2 and sometimes provide conflicting results. For these reasons, presented here is a thorough theoretical analysis of the different aspects of bulk, monolayer and bilayer MoS2 within the density functional theory (DFT) framework and with the DFT‐D3 correction to account for long‐range interactions. The crystal chemistry, stiffness, and electronic, dielectric/optical and phonon properties of single‐layered, bilayered and bulk molybdenite have been investigated, to obtain a consistent and detailed set of data and to assess the variations and cross correlation from the bulk to single‐ and double‐layer units. The simulations show the indirect–direct transition of the band gap (K–K′ in the first Brillouin zone) from the bulk to the single‐layer structure, which however reverts to an indirect transition when a bilayer is considered. In general, the optical properties are in good agreement with previous experimental measurements using spectroscopic ellipsometry and reflectivity, and with preliminary theoretical simulations. [ABSTRACT FROM AUTHOR]

Physical bending provides a more stable and controllable method to modify the electronic properties and device applications compared to chemical doping/surface modification in traditional optoelectronic materials. The bending effect on the electronic properties and nonlinear optical (NLO) responses of linear porphyrin oligomer is explored using quantum chemistry methods by designing a series of curved structures with different bending degrees. The highest occupied molecular orbital−lowest unoccupied molecular orbital energy gap (Egap) of the linear porphyrin oligomer decreases after being bended to form the curved structures, and the Egap values and orbital distributions show independent behavior on bending degree. In the electronic absorption spectra, the maximum absorptions mainly come from the S0 → S1/S0 → S2 transitions with the characteristic of local excitation. The NLO response presents a tendency to increase and then decrease with decreasing the bending degree, which is in good accordance with the widely used two‐level model. The curved frameworks as well as the results offer guidelines for novel organic NLO device design and fabrication. [ABSTRACT FROM AUTHOR]

The rapid development of modern quantum mechanical theories and computational resources facilitates extended characterization of molecular systems of increasing size and complexity, including chromophores of biochemical or technological interest. Efficient and accurate computations of molecular structure and properties in the ground and excited electronic states are routinely performed using density functional theory (DFT) and its time-dependent (TD-DFT) counterpart. However, the direct comparison with experiment requires simulation of electronic absorption or emission spectra, for which inclusion of vibrational effects leads to more realistic line shapes while at the same time allowing for more reliable interpretation and prediction of optical properties and providing additional information that is not available from experimental low-resolution UV-vis spectra. Computational support can help identify the most interesting chromophores among a large number of potential candidates for designing new materials or sensors, as well as unraveling effects contributing to the overall spectroscopic phenomena. In this perspective, recently developed viologen derivatives (1,1′-disubstituted-4,4′-bipyridyl cation salts, viol) are selected as test cases to illustrate the advantages of spectroscopic theoretical methodologies, which are still not widely used in “chemical” interpretation. Although these molecules are characterized by improved stability as well as the dual function of chromism and luminescence, their detailed spectroscopic characterization is hampered due to the availability of only low-resolution experimental spectra. DFT-based absorption and emission spectra are exploited in the analysis of optical properties, allowing detailed investigation of vibrational effects and gaining more insights on the structure–spectra relationship, which can be extended to develop further viologen dyes with improved optical properties.

In this paper, we propose the novel ZrTeS4 single layer and investigate its properties using first-principles calculations. In the equilibrium state, the ZrTeS4 single layer has an anisotropic lattice with high structural stability. The direct band gap of ZrTeS4 is found to be approximately 1.89 eV. Like other narrow-band-gap 2D materials, ZrTeS4 is rather ductile, however its Poisson's ratio is close to that of graphene. Single-layer ZrTeS4 is expected to be a promising non-linear optical material due to its good birefringence and perfect transparency in most of the infrared region. Single-layer ZrTeS4 is favorable for hole–electron separation because it only allows fast mobility of electrons along the x-axis. The absorption coefficient α(ω) is very high in the visible region (at 105 cm−1) and ultra-violet region (at 106 cm−1). The electronic and optical properties of single-layer ZrTeS4 can be tuned by applying different strains. It is reasonable to suggest single-layer ZrTeS4 as a good candidate for optoelectronic applications. [ABSTRACT FROM AUTHOR]

Cerium oxide nanoparticles were obtained using aqueous extracts of Chelidonium majus and Viscum album. X-ray diffractometry analysis confirmed the crystalline structure of the synthesized cerium oxide nanoparticles calcined at 600 °C. Scanning electron microscopy, UV-Vis reflectance and Raman spectroscopy, XPS, and fluorescence studies were utilized to interpret the morphological and optical properties of these nanoparticles. The STEM images revealed the spherical shape of the nanoparticles and that they were predominantly uniform in size. The optical band gap of our cerium nanoparticles was determined to be 3.3 and 3.0 eV from reflectance measurements using the Tauc plots. The nanoparticle sizes evaluated from the Raman band at 464 cm−1 due to the  F 2 g  mode of the cubic fluorite structure of cerium oxide are close to those determined from the XRD and STEM data. The fluorescence results showed emission bands at 425, 446, 467, and 480 nm. The electronic absorption spectra have exhibited an absorption band around 325 nm. The antioxidant potential of the cerium oxide nanoparticles was estimated by DPPH scavenging assay. [ABSTRACT FROM AUTHOR]

We have used density functional theory and the SIESTA code to investigate the electronic bandgap and optical spectra of zigzag boron nitride nanoribbons n-ZBNNRs (n = 18, 22, 26, 30). The electronic structure of the simulated nanoribbons reveals that they are semiconductors with a bandgap of 4.87–4.95 eV. For energies greater than 5 eV, the real part of the dielectric function suggests that ZBNNRs are negative refractive index materials. n-ZBNNRs also have a lower static refractive index than armchair graphene nanoribbons. The fundamental reason is that the boron nitride nanoribbons have more localized electrons. The optical absorption of n-ZBNNRs (n = 18, 22, 26, 30) is anisotropic for the x, y, and z polarizations as well. Moreover, Eoptical gap18-BNNRs = 4.95 eV, Eoptical gap22-BNNRs = 4.94 eV, Eoptical gap26-BNNRs = 4.92 eV, and E optical gap30-BNNRs = 4.87 eV. The maximum optical extinction occurs at E ≈ 6–7 eV for the y polarization and E ≈ 5–6 eV for the z-direction. Besides, by around 6 eV for the y polarization (and 5 eV for the z polarization), σ is almost 1500 Ω−1 cm−1 (and 860–1500 Ω−1 cm−1). The imaginary part of the optical conductivity indicates that for the low energy range, n-ZBNNRs (n = 18, 22, 26, 30) supply the conditions of the transverse-electric mode existence. In addition, for E y > 6 eV and E x > 5 , n-ZBNNRs (n = 18, 22, 26, 30) support the transverse-magnetic plasmons. [ABSTRACT FROM AUTHOR]

The Knoevenagel condensation of azulenyl ketones with malononitrile resulted in the synthesis of π-conjugated 1-mono- and 1,3-bis(phenyldicyanovinyl)azulenes, and the Kumada cross-coupling reaction of bromazulenes with PhMgBr gave 1-mono- and 1,3-biphenylazulene. The electronic spectra of dicyanovinylated azulenes showed strong absorption bands of intramolecular charge transfer in the visible region, as well as significant bathochromic shifts of the absorption maxima of phenylazulenes. [ABSTRACT FROM AUTHOR]

The effect of substitution of Cr in 2H‐CrSe2 by Fe and Co on its electronic, optical, and magnetic properties is studied by first‐principles density functional theory. Spin‐polarized semiconducting state is realized in CrSe2 by substitutional doping of Fe and Co, while a semimetallic state is obtained by Fe doping and the magnetic moment after Fe doping is 4.52 μB. On Co substitution, it is observed that the system presents metallic properties, with relatively low light absorption and reflectance, and good transparency. The magnetic moment after Co doping is 2.71 μB. The absorption coefficient of CrSe2 to visible light increases with the doping of Fe and Co, and the peak value is redshifted, which is conducive to the further application of CrSe2 in the field of optoelectronics. [ABSTRACT FROM AUTHOR]

Linear, nonlinear and total optical absorption coefficients and relative refractive index changes for symmetric and asymmetric double V-shaped quantum well configurations formed within AlxGa1-xAs/GaAs heterostructure have been theoretically investigated. Responses of these coefficients to well widths, barrier widths and aluminium concentrations within the barrier as well as applied external electromagnetic fields were the subject of this study. The electronic spectra of the structures are obtained as a solution to the Schrödinger equation with relevant potential and external agents in the framework of effective mass and envelope wave function approximations. The optical properties are calculated by the analytical expressions obtained by iterative solutions within the compact density matrix approach. Although increasing barrier width and aluminium concentration act similarly significant red shifting on the referred coefficients for both symmetric and asymmetric double V-shaped wells, the varying well widths act differently for each configuration. Strengthening electric and magnetic fields shift the resonance peaks to blue for both symmetric and asymmetric wells. The results show that optical properties can be controlled by structural parameters, external probes and asymmetry of double V-shaped wells. [ABSTRACT FROM AUTHOR]

MoO3 and MoO2 systems have attracted particular attention for many widespread applications thanks to their electronic and optical peculiarities; from the crystallographic point of view, MoO3 adopts a thermodynamically stable orthorhombic phase (α-MoO3) belonging to the space group Pbmn, while MoO2 assumes a monoclinic arrangement characterized by space group P21/c. In the present paper, we investigated the electronic and optical properties of both MoO3 and MoO2 by using Density Functional Theory calculations, in particular, the Meta Generalized Gradient Approximation (MGGA) SCAN functional together with the PseudoDojo pseudopotential, which were used for the first time to obtain a deeper insight into the nature of different Mo–O bonds in these materials. The calculated density of states, the band gap, and the band structure were confirmed and validated by comparison with already available experimental results, while the optical properties were validated by recording optical spectra. Furthermore, the calculated band-gap energy value for the orthorhombic MoO3 showed the best match to the experimental value reported in the literature. All these findings suggest that the newly proposed theoretical techniques reproduce the experimental evidence of both MoO2 and MoO3 systems with high accuracy. [ABSTRACT FROM AUTHOR]

Most known compounds with five‐coordinated Ti4+ are natural and synthetic titanosilicates. The crystal structure of natural fresnoite, Ba2TiSi2O8 [tetragonal, space group P4bm, a = 8.510 (1) Å, c = 5.197 (1) Å, V = 376.4 (1) Å3, Z = 2], has been refined to R = 0.011 on the basis of 807 unique single‐crystal reflections with I > 2σ(I). Titanium has fivefold coordination with one short ('titanyl') bond of 1.692 (5) Å. Bonds in the TiO5 polyhedron are discussed in comparison to analogous coordination polyhedra in other minerals and compounds. A review of all known compounds with Ti4+O5 polyhedra shows that most of them are titanosilicates in which titanium forms a short Ti—O bond (∼1.61 to ∼1.77 Å). Poor Gladstone–Dale compatibility between chemical composition, optical characteristics and density of these compounds is explained by the anomalous contribution of [5]Ti4+ to the optical properties as shown by calculations based on the relationship between electronic polarizabilities and refractive indices. An improved Gladstone–Dale coefficient of 0.29 is suggested for TiO2 with [5]Ti4+. A negative correlation between 'titanyl' bond lengths and wavenumbers of the bands of Ti—O stretching vibrations (in the range of 890–830 cm−1) in infrared and Raman spectra is observed. [ABSTRACT FROM AUTHOR]

Context: Comparatively, metal-free sensitizers featuring the chalcogen family receive less attention despite known electronic properties for metal-chalcogenide materials. This work reports an array of optoelectronic properties using quantum chemical methods. Observed red-shifted bands within the UV/Vis to NIR regions with absorption maxima > 500 nm were consistent with increasing chalcogenide size. There is a monotonic down-shift in the LUMO and ESOP energy consistent with O 2p, S 3p, Se 4p, to Te 5p atomic orbital energies. Excited-state lifetime and charge injection free energies follow the decreasing order of chalcogenide electronegativity. Adsorption energies of dyes on TiO2 anatase (101) range between − 0.08 and − 0.77 eV. Based on evaluated properties, selenium- and tellurium-based materials show potential use in DSSCs and futuristic device applications. Therefore, this work motivates continued investigation of the chalcogenide sensitizers and their application. Methods: The geometry optimization was performed at B3LYP/6–31 + G(d,p) and B3LYP/LANL2DZ level of theory for lighter and heavier atoms, respectively, using Gaussian 09. The equilibrium geometries were confirmed by the absence of imaginary frequencies. Electronic spectra were obtained at CAM-B3LYP/6-31G + (d,p)/LANL2DZ level of theory. Adsorption energies for dyes on a 4 × 5 supercell TiO2 anatase (101) were obtained using VASP. The dye-TiO2 optimizations were employed using GGA and PBE with the PAW pseudo-potentials. The energy cutoff was set at 400 eV and convergence threshold for self-consistent iteration was set to 10−4, and van der Waals were accounted using DFT-D3 model and on-site Coulomb repulsion potential set at 8.5 eV for Ti. [ABSTRACT FROM AUTHOR]

[Display omitted] The monoclinic crystal system β-gallium oxide (β-Ga 2 O 3) is an advantageous semiconductor, characterized by a substantial bandgap of approximately 4.8 eV, exceptional stability under ambient conditions, and transparency to ultraviolet (UV) light. In practical applications, it is critical to effectively manage defects within β-Ga 2 O 3. Failure to rigorously control defect types and concentrations can significantly compromise device stability and reliability. Among the prevalent and impactful defects, Ga intrinsic vacancies notably affect the optoelectronic performance of β-Ga 2 O 3 , yet they have not been comprehensively studied using suitable generalized approximations. This paper systematically examines the electronic and optical properties of β-Ga 2 O 3 with intrinsic Ga vacancies using hybrid functional methods combined with the shell DFT-1/2 approach. Key properties analyzed include electronic bandgap and density of states, structural properties like elastic constants and phonon dispersion, and optoelectronic properties such as permittivity, absorption spectra, and electronic energy-loss spectra. Detailed discussion is provided on the formation energy curves of these Ga intrinsic defects. [ABSTRACT FROM AUTHOR]

The present study deals with the investigation of the change in the hyperpolarizability of Pentacene-2,5-dione (PD) on the introduction of the gold (Au) and silver (Ag) nanoclusters using the density functional theory (DFT). The involvement of the nanoclusters induces the intramolecular interactions, which is confirmed by the electrostatic potential plot and Mulliken charge distribution. The process of adsorption of metal clusters on the surface of PD is investigated by absorption spectra and the Raman spectra analysis. The global reactivity parameters validate a hike in the reactivity of the PD after the adsorption of Ag3 and Au3 nanoclusters. The study reported extraordinary enhancement in the hyperpolarizability of the metal nanoclusters adsorbed complexes. The high value of hyperpolarizability for PD-Ag3 (184.22 × 10−30esu) and PD-Au3 (2057.26 × 10−30esu) validates their applications in highly efficient NLO devices. The statistical calculation of radiative lifetime and light-harvesting efficiency reveals that probe PD can fruitfully contribute to the development of photo luminescent material and photosensitizer dye in dye-synthesized solar cells. [ABSTRACT FROM AUTHOR]

The electronic and optical properties of N-doped narrow tellurene nanoribbons (TeNRs) were studied using first-principles calculations. The results show that the formation energies of N-doped TeNRs are lower than those of pristine TeNRs, which indicate that N-doped TeNRs are more stable. Due to the small radius and large electronegativity of N atoms, the edge structures of N-doped TeNRs reorganized. In the ribbon width range in our study, for the presence or absence of spin–orbit coupling, N-doped TeNRs are semiconductors, and their direct bandgaps decrease with increasing ribbon width. The imaginary and real parts of the dielectric functions of N-doped TeNRs were different, indicating that N-doped TeNRs exhibit optical anisotropy. The peak value of the real part reaches 71.55; thus, it can be used in high-k dielectric-based devices. These findings on one-dimensional elemental tellurium nanostructures effectively extend the realm of group VI elements. [ABSTRACT FROM AUTHOR]