Local Function Research Articles

Signature of excitonic insulators in phosphorene nanoribbons

Phosphorene is a recently developed two-dimensional (2D) material that has attracted tremendous attention because of its unique anisotropic optical properties and quasi-one-dimensional (1D) excitons. We use first-principles calculations combined with the maximally localized Wannier function tight binding Hamiltonian and Bethe–Salpeter equation (BSE) formalism to investigate quasiparticle effects of 2D and quasi-1D blue and black phosphorene nanoribbons. Our electronic structure calculations shows that both blue and black monolayered phases are semiconductors. On the other hand black phosphorene zigzag nanoribbons are metallic. Similar behavior is found for very thin blue phosphorene zig-zag and armchair nanoribbon. As a general behavior, the exciton binding energy decreases as the ribbon width increases, which highlights the importance of quantum confinement effects. The solution of the BSE shows that the blue phosphorene monolayer has an exciton binding energy four times higher than that of the black phosphorene counterpart. Furthermore, both monolayers show a different linear optical response with respect to light polarization, as black phosphorene is highly anisotropic. We find a similar, but less pronounced, optical anisotropy for blue phosphorene monolayer, caused exclusively by the quasi-particle effects. Finally, we show that some of the investigated nanoribbons show a spin-triplet excitonic insulator behavior, thus revealing exciting features of these nanoribbons and therefore provides important advances in the understanding of quasi-one dimensional phosphorus-based materials.

Rasch analysis of the self efficacy (SE-12) questionnaire measuring clinical communication skills

ObjectiveThe aim of this study was to examine the construct validity and reliability of the Self Efficacy (SE-12) questionnaire using Rasch analysis. MethodsThe SE-12 was administered to Danish health care professionals prior to their participation in a communication skills training program. Analysis of fit to the Rasch model, ordering of response categories, dimensionality-testing, test for differential item functioning, test for local dependency, and calculation of reliability were used to evaluate the psychometric characteristics of the SE-12. ResultsIn this study, 1057 respondents were analyzed. Overall, the SE-12 demonstrated an acceptable fit to the Rasch model. Response categories were appropriately ordered for all twelve items. However, items 6 (structure) and item 8 (empathy) demonstrated differential item functioning, with men being more likely to affirm the first and women the last item. Local dependency was observed between five item groups but adjusting for these improved fit indices significantly. The SE-12 exhibited high reliability with PSI ranging from 0.92 to 0.94. A transformation table converting ordinal scores to interval scores is provided. ConclusionThe SE-12 demonstrates good construct validity and excellent reliability. Minor issues regarding local dependency and differential functioning require attention.Innovation: A 5-item version could be explored without compromising validity and reliability.

Preparation of a Novel Multifunctional Cationic Liposome Drug-carrying System and its Functional Study on Lung Cancer.

Low-dose chemotherapy is a promising treatment strategy that may be improved by controlled delivery. This study aimed to design polyethylene glycol-stabilized bilayer-decorated magnetic Cationic Liposomes (CLs) as a drug delivery system for integrated functional studies of lung cancer cell therapy and imaging. A novel multifunctional folic acid targeting magnetic CLs docetaxel drug-loading system (FA-CLs-Fe- DOC) was prepared and tested for its physical properties, encapsulation rate and drug release performance. The feasibility of FA-CLs-Fe-DOC ability to inhibit tumor cells and act as an MRI contrast agent was investigated in vitro, and the target recognition and therapeutic ability of FA-CLs-Fe-DOC was studied in vivo. FA-CLs-Fe-DOC had a particle size of 221.54 ± 6.42 nm and a potential of 28.64 ± 3.56 mv, with superparamagnetic properties and better stability. The encapsulation rate was 95.36 ± 1.63%, and the drug loading capacity was 9.52 ± 0.22%, which possessed the drug slow-release performance and low cytotoxicity and could effectively inhibit the proliferation of lung cancer cells, promoting apoptosis of lung cancer cells. MRI showed that it had the function of tracking and localization of lung cancer cells. In vivo experiments confirmed the targeted recognition property and therapeutic function of lung cancer cells. In this study, we successfully prepared an FA-CLs-Fe-DOC capable of specifically targeting lung cancer cells with integrated functions of efficient lung cancer cell killing and imaging localization. This targeted drug packaging technology may provide a new strategy for the design of integrated carriers for targeted cancer therapy and imaging.

Vaginal or Fecal Contamination Which Contributes to Parasite Existence in Urine Sediment

Aims: intended to deepen our knowledge to date regarding parasites that might found in urine sediment as consequences of vaginal or fecal contamination during voiding Discussion: Urine in the bladder is a sterile waste product composed of water soluble nitrogen products. But during voiding, the passage of the urine through lower/outer portion of the urinary tract might come across normal microbiota which function in maintaining the urothelial integrity and preventing urinary tract infection (UTI), as well as promoting local immune function. Parasites and parasitic ova may be seen in urinary sediments as a result of fecal or vaginal contamination. Identification of parasites in centrifuged deposits of urine sediment is a relatively rare occurrence in clinical practice but still must be considered carefully, whether as a consequence of contamination or definite causes of infection. Two of the common parasite found in urine sediment are Trichomonas vaginalis and Enterobius vermicularis. Urine collection procedure must be explained briefly to the patient along with appropriate informed consent prior obtaining the sample. Conclusion: The possibility of parasites being found in urine sediment remain to happen. An in-depth analysis needs to be carried out to determine whether this occurs due to vaginal or rectal contamination or whether it is due to a definitive infection occurring in the urinary tract.

Automatic State Interaction with Large Localized Active Spaces for Multimetallic Systems.

The localized active space self-consistent field method factorizes a complete active space wave function into an antisymmetrized product of localized active space wave function fragments. Correlation between fragments is then reintroduced through localized active space state interaction (LASSI), in which the Hamiltonian is diagonalized in a model space of LAS states. However, the optimal procedure for defining the LAS fragments and LASSI model space is unknown. We here present an automated framework to explore systematically convergent sets of model spaces, which we call LASSI[r, q]. This method requires the user to select only r, the number of electron hops from one fragment to another, and q, the number of fragment basis functions per Hilbert space, which converges to CASCI in the limit of r, q → ∞. Numerical tests of this method on the trimetal oxo-centered complexes [Fe(III)Al(III)Fe(II)(μ3-O)(HCOO)6] and [Fe(III)2Fe(II)(μ3-O)(HCOO)6] show efficient convergence to the CASCI limit with 4-10 orders of magnitude fewer states than CASCI.

Moderately dense granular gas of inelastic rough spheres

A kinetic theory for moderately dense gases of inelastic and rough spherical molecules is developed from the Enskog equation where a macroscopic state is characterised by 29 scalar fields which correspond to the moments of the distribution function: mass density, hydrodynamic velocity, pressure tensor, absolute temperature, translational and rotational heat fluxes, hydrodynamic angular velocity and angular velocity flux. The balance equations for the 29 scalar fields are obtained from a transfer equation derived from the Enskog equation where the kinetic and potential parts of the new moments of the distribution function and production terms are calculated from Grad’s distribution function for the basic fields. The transition from the 29 field theory to an eight field theory—with mass density, hydrodynamic velocity, absolute temperature and hydrodynamic angular velocity—leads to the determination of the transport coefficients of the Navier–Stokes and Fourier laws. The transport coefficients are functions of the normal and tangential restitution coefficients and of the local equilibrium radial distribution function. The transport coefficients in the limiting case of elastic rough spheres is also determined.

Theoretical investigation of gas sensing properties of a monolayer gallenene: First-principles insight

Two dimensional (2D) materials exhibit potential to be used in thin film electronic devices. In present paper, we explore 2D polymorphs of α-Ga by performing ab−initio calculations based on density functional theory. Phonon calculations show that Ga100 and Ga010 planes are dynamically stable at 6% and 2% bi-axial tensile strain. The ab-initio molecular dynamics calculations show that while Ga100 plane retain structural stability in a free standing state for temperature up to 500 K, Ga010 plane shows structure distortion which further increases with increase in temperature. We find total energy of Ga010 plane is smaller (−1.09 eV/f.u.) than Ga100 plane, indicating that Ga010 plane is energetically more stable. We next follow the adsorption of toxic gas molecule over Ga010 plane, referred as gallenene sheet. The negative adsorption energy shows that adsorption of phosgene (CCl2O), hydrogen cyanide (HCN), phosphine (PH3), and hydrogen selenide (H2Se) gas molecule over gallenene sheet is feasible. We find that (CCl2O) H2Se gas (weakly) strongly interact with gallenene with adsorption energy of (−0.39 eV) −0.52 eV. Bader charge calculation shows transfer of electronic charge between adsorbed gas molecule and gallenene sheet, which further confirmed by plot of electron localization function (ELF). The recovery time of desorption for CCl2O (PH3) gas comes 3.90×10−6 s (2.85×10−4 s) due to greater (smaller) out of plane distance of 2.93 Å (2.75 Å). The current–voltage (I–V) characteristic shows small deviation due to lower concentration of gases over gallenene, which further confirmed by transmission spectra. We hope that our theoretical predictions will help experimentalists to synthesize gallenene based gas sensors.

Illuminating the function of the orphan transporter, SLC22A10, in humans and other primates

SLC22A10 is an orphan transporter with unknown substrates and function. The goal of this study is to elucidate its substrate specificity and functional characteristics. In contrast to orthologs from great apes, human SLC22A10, tagged with green fluorescent protein, is not expressed on the plasma membrane. Cells expressing great ape SLC22A10 orthologs exhibit significant accumulation of estradiol-17β-glucuronide, unlike those expressing human SLC22A10. Sequence alignments reveal a proline at position 220 in humans, which is a leucine in great apes. Replacing proline with leucine in SLC22A10-P220L restores plasma membrane localization and uptake function. Neanderthal and Denisovan genomes show proline at position 220, akin to modern humans, indicating functional loss during hominin evolution. Human SLC22A10 is a unitary pseudogene due to a fixed missense mutation, P220, while in great apes, its orthologs transport sex steroid conjugates. Characterizing SLC22A10 across species sheds light on its biological role, influencing organism development and steroid homeostasis.

In Silico Design and Characterization of a New Molecular Electride: Li@Calix[3]Pyrrole.

Electrides, in which anionic electrons are localized independently of the atoms in the compound, have shown promise, especially as catalysts and optoelectronic materials. Here, we present a new computationally designed molecular electride, Li@calix[3]pyrrole (Li@C3P). Electron density and electron localization function analyses unequivocally confirm the existence of localized electride electron density, outside the system, independent of any specific atoms. Non-covalent interaction plots further validate the character of the isolated localized electron, suggesting that the system can be accurately represented by Li+@calix[3]pyrrole ⋅ e-, denoting its distinct charge separation. The remarkable non-linear optical properties of Li@C3P, including average polarizability, =412.4 au, first hyperpolarizability, β=4.46×104 au, and second hyperpolarizability, =18.40×106 au, are unparalleled in the previously reported and similar Li@C4P molecular electride. Furthermore, energy decomposition analysis in combination with natural orbital for chemical valence theory sheds light on the mechanism of electron density transfer from Li to the C3P cage, yielding the charge-separated Li@C3P complex. In addition to the electron transfer, a key factor to its electride nature is the electronic structure of the CnP cage, which has its lowest unoccupied molecular orbital located in the void adjacent to the N-H groups at the back of the bowl-shaped CnP cage.

Zinc chloride-assisted activation of açaí biomass for herbicide removal: Insights from adsorption and molecular modeling

In addressing the environmental impact of açaí pulp production waste, this study explores the sustainable transformation of Euterpe oleracea fruit pits into activated carbon using a zinc chloride (ZnCl2) activation process. The primary aim is to repurpose this agricultural by-product for the efficient removal of atrazine (ATZ) and 2,4-dichlorophenoxyacetic acid (2,4-D) herbicides from contaminated water. The produced activated carbon demonstrated superior adsorptive properties, with a specific surface area (SBET) of 920.5 m2 g-1, substantial pore volume (Vp) of 0.467 cm3 g-1, and an average pore diameter (Dp) of 1.126 nm, showcasing its potential as an effective adsorbent. Experimental adsorption tests revealed that this carbonized material could remove up to 95% of ATZ and 89% of 2,4-D under optimized conditions. Advanced techniques, including Density Functional Theory (DFT) simulations and COSMO-RS analysis, provided profound insights into the adsorption mechanisms, particularly emphasizing the crucial role of hydrogen bonding interactions. Identified as key mediators, hydrogen bonding-induced contact energy facilitated herbicide adsorption, corroborated by Electron Localization Function (ELF) analysis. These findings not only suggest a viable method for mitigating the environmental issue posed by açaí pulp waste but also contribute to the development of eco-friendly adsorbents for water purification. The research underscores the potential of using biomass waste for environmental remediation, aligning with global sustainability objectives.

Kinetic equation for stochastic vector bundles

The kinetic equation is crucial for understanding the statistical properties of stochastic processes, yet current equations, such as the classical Fokker–Planck, are limited to local analysis. This paper derives a new kinetic equation for stochastic systems on vector bundles, addressing global scale randomness. The kinetic equation was derived by cumulant expansion of the ensemble-averaged local probability density function, which is a functional of state transition trajectories. The kinetic equation is the geodesic equation for the probability space. It captures global and historical influences, accounts for non-Markovianity, and can be reduced to the classical Fokker–Planck equation for Markovian processes. This paper also discusses relative issues concerning the kinetic equation, including non-Markovianity, Markov approximation, macroscopic conservation equations, gauge transformation, and truncation of the infinite-order kinetic equation, as well as limitations that require further attention.

Neuronal Coupling Modes Show Differential Development in the Early Cortical Activity Networks of Human Newborns.

The third trimester is a critical period for the development of functional networks that support the lifelong neurocognitive performance, yet the emergence of neuronal coupling in these networks is poorly understood. Here, we used longitudinal high-density electroencephalographic recordings from preterm infants during the period from 33 to 45 weeks of conceptional age (CA) to characterize early spatiotemporal patterns in the development of local cortical function and the intrinsic coupling modes [ICMs; phase-phase (PPCs), amplitude-amplitude (AACs), and phase-amplitude correlations (PACs)]. Absolute local power showed a robust increase with CA across the full frequency spectrum, while local PACs showed sleep state-specific, biphasic development that peaked a few weeks before normal birth. AACs and distant PACs decreased globally at nearly all frequencies. In contrast, the PPCs showed frequency- and region-selective development, with an increase of coupling strength with CA between frontal, central, and occipital regions at low-delta and alpha frequencies together with a wider-spread decrease at other frequencies. Our findings together present the spectrally and spatially differential development of the distinct ICMs during the neonatal period and provide their developmental templates for future basic and clinical research.

Temporal dissociation between local and global functional adaptations of the maternal brain to childbirth: a longitudinal assessment.

The maternal brain undergoes significant reorganization during birth and the postpartum period. However, the temporal dynamics of these changes remain unclear. Using resting-state functional magnetic resonance imaging, we report on local and global brain function alterations in 75 mothers in their first postpartum week, compared to 23 nulliparous women. In a subsample followed longitudinally for the next six months, we observed a temporal and spatial dissociation between changes observed at baseline (cluster mass permutation: pFWE < 0.05). Local activity and connectivity changes in widespread neocortical regions persisted throughout the studied time period (ANCOVAs vs. controls: pFDR < 0.05), with preliminary evidence linking these alterations to behavioral and psychological adaptations (interaction effect with postpartum time: uncorrected p < 0.05). In contrast, the initially reduced whole-brain connectivity of putamen-centered subcortical areas returned to control levels within six to nine weeks postpartum (linear and quadratic mixed linear models: pFDR < 0.05). The whole-brain spatial colocalization with hormone receptor distributions (Spearman correlations: pFDR < 0.05) and preliminary blood hormone associations (interaction effect with postpartum time: uncorrected p < 0.05) suggested that the postpartum restoration of progesterone levels may underlie this rapid normalization. These observations enhance our understanding of healthy maternal brain function, contributing to the identification of potential markers for pathological postpartum adaptation processes, which in turn could underlie postpartum psychiatric disorders.

Neuromorphic place cells

A neuromorphic simultaneous localization and mapping (SLAM) system shows potential for more efficient implementation than its traditional counterpart. At the mean time a neuromorphic model of spatial encoding neurons in silicon could provide insights on the functionality and dynamic between each group of cells. Especially when realistic factors including variations and imperfections on the neural movement encoding are presented to challenge the existing hypothetical models for localization. We demonstrate a mixed-mode implementation for spatial encoding neurons including theta cells, egocentric place cells, and the typical allocentric place cells. Together, they form a biologically plausible network that could reproduce the localization functionality of place cells observed in rodents. The system consists of a theta chip with 128 theta cell units and an FPGA implementing 4 networks for egocentric place cells formation that provides the capability for tracking on a 11 by 11 place cell grid. Experimental results validate the robustness of our model when suffering from as much as 18% deviation, induced by parameter variations in analog circuits, from the mathematical model of theta cells. We provide a model for implementing dynamic neuromorphic SLAM systems for dynamic-scale mapping of cluttered environments, even when subject to significant errors in sensory measurements and real-time analog computation. We also suggest a robust approach for the network topology of spatial cells that can mitigate neural non-uniformity and provides a hypothesis for the function of grid cells and the existence of egocentric place cells.

Molecular structure, optical, first-order hyper polarizability, electronic properties, reactivity (ELF and LOL) − computational analysis using DFT and Multiwfn for 2, 3-diaminopyridinium selenate

A detailed study on the first principle calculations of 2,3-diaminopyridinium selenite (2,3-DAPS) – an organometallic salt has been performed using B3LYP/6–311++G(d,p). Single crystal X-ray diffraction (XRD) analysis confirms that the crystal formed exhibits a monoclinic crystal structure, specifically belonging to the centrosymmetric space group P21/c. The obtained primitives and interfacial angles are as follows: a = 7.4978(15)Å, b = 7.6681(15) Å, c = 14.314(3) Å, α = γ = 90°, β = 93.75(3)°, and the volume of the unit cell V = 821.2(3) (Å)3. The structure was optimized with a global minimum. The natural bonding orbital charge transfer studies between the cation and anion was performed to gain insights into their electronic interactions. Energy gap and other global chemical reactivity descriptors have been computed with the aid of molecular orbital studies. The influence of solvent on the absorption spectra provided the evidence of solvent–solute interactions and their impact on the electronic transitions within the molecule. The presence of electrophilic and nucleophilic reactivity in the chemical is indicated by the molecular electrostatic potential (MEP) map. From the nonlinear optical (NLO) studies, it has been found that the first-order hyperpolarizability value is 30.771 × 10−31 esu, which is 8.252 times that of urea. This suggests that the compound may be a better non-linear optical material and suitable for laser applications. To calculate the proportion of intermolecular interactions and examine the distribution compound's electrostatic potential, a Hirshfeld surface analysis was conducted. The analysis provided insights into the spatial arrangement of molecules and their interactions. Additionally, topology path calculations elucidated the intrinsic connectivity between critical points, shedding light on the bonding characteristics within the compound. The likelihood of electron density at bonding and anti-bonding sites was also determined using the Electron Localization Function (ELF) and Localised Orbital Locator (LOL) plots. These analyses aided in understanding the electron distribution and the nature of chemical bonding within the compound, providing valuable information about its electronic structure and reactivity.

Exploring the effects of mono-bromination on hole-electron transport and distribution in dibenzofuran and dibenzothiophene isomers: a first-principles study.

This study delves into hole-electron transport and distribution properties inherent in mono-brominated dibenzofuran (DBF) and dibenzothiophene (DBT) isomers. As determined by frontier molecular orbitals, all brominated structures have narrower bandgaps than their primary structures. The TD-DFT calculation showed that 2BDBT had the highest absorption wavelength of all molecules at 315.35nm. Notably, the study unveils remarkably low electron and hole reorganization energies due to bromine substitution in DBF and DBT molecules. Specifically, the 4BDBF has the lowest hole reorganization energy of all DBF configurations, 0.229eV. In addition, 3BDBF has 0.226eV less electron reorganization energy than all other molecules. Compared to DBT, 3BDBT has the lowest electron reorganization energy of 0.254eV. Overall, this research sheds significant light on the fundamental electronic and hole transport characteristics of bromine-substituted DBF and DBT isomers, highlighting their promising role in polymer design as donors/acceptors for advanced organic electronic applications. Molecular structures were optimized using Density Functional Theory (DFT) B3LYP/6-311 + + G (d, p) level of theory, and the study further elucidates these molecules' energy levels and absorption spectra through Time-Dependent Density Functional Theory TD-DFT; these calculations were performed using Gaussian 09W software package. The key parameters such as reorganization energies, Electron Localization Function map, Laplacian Bond Order, and NCI-RDG were meticulously examined for the molecules with the results of DFT calculations were analyzed and displayed by utilizing the software packages VMD 1.9.4 and Multiwfn 3.8, aiming to comprehend their charge transport and distribution properties.

Concentration effects on the local structures and electronic properties of Er x BaY2− x F8: a first-principles study

Er3+ doped barium yttrium fluoride (BaY2F8) crystal has gained long-term attention due to its great potential in laser and medical device applications. However, the local structures of Er3+ doped BaY2F8 system (Er:BYF) remain uncertain, and the effect of doping concentration on structures and properties is unknown. Therefore, in this study, the first-principles study of the structural evolution of Er x BaY2−x F8 (x = 0.125, 0.25) crystals was carried out. By means of density functional theory and particle swarm optimization algorithm, the stable structures of Er:BYF crystals with two different concentrations are shown as standard monoclinic structures with P2 symmetry for the first time. The impurity Er3+ ions successfully enter the main lattice, replacing the Y3+ ions, and forming a [ErF8]5− polyhedron with C 2 point group symmetry. By calculating the electronic properties, the band gap values of the two structures are significantly reduced compared with that of pure BaY2F8 crystal. However, the conduction band does not break through the Fermi level, and the crystals still maintain the insulation characteristic. According to the calculation of the electron local density function, we conclude that Er–F and Y–F in Er:BYF are connected by ionic bonds. These results fill a theoretical gap in the study of Er:BYF crystals and provide inspiration for structural evolution and material design at different doping concentrations.

P38 Experimental evidence of ecto-5′-nucleotidase (CD73) modulation in psoriasis-like inflammation

Abstract Introduction and aims Adenosine is an endogenous purine nucleoside that, by binding to adenosine receptors, modulates inflammation and immune responses. Psoriasis is a chronic immune-mediated inflammatory skin disease characterized by keratinocyte hyperproliferation and abnormal differentiation. A2A and A2B adenosine receptors modulate keratinocyte proliferation and their expression was found to be altered in psoriatic epidermis. Ecto-5′-nucleotidase (CD73) is an enzyme that hydrolyses extracellular adenosine monophosphate and represents a key control point for extracellular adenosine accumulation. CD73 is involved in the regulation of local immune response and tissue barrier function. As changes in CD73 expression and activity have been associated with other autoimmune diseases, the aim of this study was to investigate CD73 involvement in skin inflammation using in vitro and in vivo approaches. Methods In vitro experiments were performed on human keratinocyte (HaCaT) cell lines stimulated with tumour necrosis factor-α, interleukin (IL)-17A, IL-6 and IL-1α (10 ng mL−1 each), and in vivo, on the mouse model of imiquimod-induced psoriasis-like inflammation on the right ear, which was also performed on CD73−/− mice and their wildtype counterpart. CD73 expression in cell lysates and ear homogenates were evaluated using Western blot analysis. Results We found that CD73 expression was significantly increased (N = 3 wells, P &amp;lt; 0.05) in cytokine-treated HaCaTs compared with unstimulated cells. In vivo experiments showed increased CD73 expression on psoriatic lesions (P &amp;lt; 0.001, N = 3). In CD73−/− mice, imiquimod-induced lesions were exacerbated compared with the development of lesions in wildtype mice as shown by ear thickness (0.190 ± 0.02 mm, knockout mice vs. 0.138 ± 0.02 mm, wildtype mice; P &amp;lt; 0.05, N = 5), erythema and scaling. Conclusions Our preliminary Results show involvement of CD73 in the development of psoriasis-like inflammation, suggesting that CD73 may represent a new therapeutic target in the treatment of skin diseases. Further investigations are needed to provide an in-depth study of CD73 localization in inflamed skin.

Conformal mapping at elevation with implications for low-distortion projections

This article develops the theory of the conformal mapping of the surface of constant height above the ellipsoid (ChS), which has implications for the design of low-distortion projections. This paper gives a development of the Mercator, polar stereographic, Lambert conformal conic (LCC) and transverse Mercator (TM) projections based on the ChS, a better Earth model than the reference ellipsoid (RE) for positions at height. This article provides new formulas for the LCC and TM inverse scale problems – when given a value for the local scale function, where does it occur? These formulas apply to both traditional mapping on the RE and novel mapping on the ChS.

Optoelectronic and photocatalytic behaviour of a type-II GaAlS2/HfS2 heterostructure: ab initio study

Theoretical examination based on first principle computation has been conducted for van der Waals heterostructure (vdwHS) GaAlS2/HfS2 including structural, optoelectronic and photocatalytic characteristics. From the adhesion energy calculation, the AB configuration of GaAlS2/HfS2 vdwHS is the most stable. A type-II GaAlS2/HfS2 vdwHS is a dynamically and thermally stable structure. The band edge position, projected band, and projected charge densities verify the type-II alignment of GaAlS2/HfS2 vdwHS. For GaAlS2/HfS2, GaAlS2 is acting as a donor and HfS2 is acting as an acceptor ensured by the charge density difference plot. The electron localized function validates the weak van der Waals interaction between GaAlS2 and HfS2. The GaAlS2/HfS2 vdwHS possess an indirect bandgap of 1.54 eV with notable absorption in the visible range. The findings assure that the GaAlS2/HfS2 vdwHS is an efficient photocatalyst for pH 4–8. The band alignment of GaAlS2/HfS2 is suitable for Z-scheme charge transfer. The strain influenced band edge suggests that the GaAlS2/HfS2 vdwHS remains photocatalytic for strain −4% to +6% in both cases of uniaxial and biaxial strains.