Local Function Research Articles

Topological structures and adsorption properties of the [Fe4S4] clusters

The [Fe4S4] compositions are ubiquitous in biological systems as integral parts of the complex catalytic mechanisms as in hydrogenases and nitrogenases. The current reports about [Fe4S4] species are based on the cube-like structure framework. Here, the topological structures, stability and electronic properties of gas phase [Fe4S4]+, [Fe4S4]0 and [Fe4S4]− are analyzed. It is found that ground state structures of these three clusters have similar cubic cages but different symmetries and spin multiplicities. The molecular dynamics simulations demonstrate that the cubic cage remains thermodynamically stable at 700 K. The density of states show that the charge state is the key to affect electronic behaviors of them even under the same structural framework. The molecular orbitals show that the LUMO orbitals are distributed throughout whole structures, showing great delocalized characteristics, especially for the anionic [Fe4S4]−, while the HOMO orbits are mainly localized in Fe-S bonds, which are also confirmed by the electron localization function analyses. After one CO molecule is adsorbed on these clusters, it prefers to locate at the Fe atoms. Moreover, the C–O bond length and vibration frequency of the [Fe4S4]−-CO undergone a significant red shift. Our work shows that the [Fe4S4]− may act as a potential catalyst for activating the C–O bond.

Polarized Raman, infrared and dielectric spectra of lead-free K0.5Na0.5NbO3 piezoelectric system: insights from ab-initio theoretical and experimental studies

The K0.5Na0.5NbO3 (KNN) system has emerged as one of the most promising lead-free piezoelectric over the years. In this work, we perform a comprehensive investigation of electronic structure, lattice dynamics and dielectric properties of room temperature phase of KNN by combining ab-initio DFT based theoretical analysis and experimental characterization. We assign the symmetry labels to KNN vibrational modes and obtain ab-initio polarized Raman spectra, Infrared reflectivity, Born-effective charge tensors, oscillator strengths etc. The KNN ceramic samples are prepared using conventional solid-state method and Raman and UV–Vis diffuse reflectance spectra are obtained. The computed Raman spectrum is found to agree well with the experimental spectrum. In particular, the results suggest that the mode in range ∼840–870 cm−1 reported in the experimental studies is longitudinal optical with A1 symmetry. The Raman mode intensities are calculated for different light polarization set-ups that suggests the observation of different symmetry modes in different polarization set-ups. The electronic structure of KNN is investigated and optical absorption spectrum is obtained. Further, the performances of DFT semi-local, meta-GGA and hybrid exchange-correlations functionals, in the estimation of KNN band gaps are investigated. The KNN bandgap computed using GGA-1/2 and HSE06 hybrid functional schemes are found to be in excellent agreement with the experimental value. The COHP, electron localization function and Bader charge analysis is also performed to deduce the nature of chemical bonding in the KNN. Overall, our study provides several bench-mark important results on KNN that have not been reported so far.

MEDT analysis of mechanism and selectivities in non-catalyzed and lewis acid-catalyzed diels–alder reactions between R-carvone and isoprene

Within the context of Molecular Electronic Density Theory (MEDT), this study investigates the Diels–Alder reaction among isoprene (2) and R-carvone (1R) applying DFT simulations, with and without Lewis acid (LA) catalysis. The results show that carvone (1R) acts as an electrophile and isoprene (2) as a nucleophile in a polar process. LA catalysis increases the electrophilicity of carvone, thereby improving the reactivity and selectivity of the reaction by reducing the activation Gibbs free energy. Parr functions reveal that the C5=C6 double bond is more reactive than the C9=C10 double bond, indicating chemoselectivity. The examination of the Electron Localization Function (ELF) reveals high regio- and stereoselectivity, indicating an asynchronous mechanism for the LA-catalyzed DA reaction. Furthermore, it is suggested that cycloadduct 3 has great anti-HIV potential because it exhibits lower binding energies than azidothymidine (AZT) in the docking studies of cycloadducts 3 and 4 amongst a primary HIV-1protein (1A8O plus 5W4Q).

ANALISIS KESELAMATAN JALAN DENGAN PENDEKATAN AUDIT KESELAMATAN JALAN PADA JALAN LOKAL DI KOTA TEGAL

Jalan Sultan Hasanudin – KH. Abdul Ghoni, which is located in Tegal City, Central Java, is a road with a secondary local function which is an alternative way to get to primary roads. By being an alternative road, this road section must meet adequate road safety standards. To improve traffic safety, it is necessary to carry out a road safety audit. This research aims to see the level of road safety in Tegal City, specifically on the Jalan Sultan Hasanudin - Jalan KH section. Abdul Ghoni. The method used in this research is descriptive quantitative obtained from the Hawkeye survey and processed using the Hawkeye processing toolkit software to analyze the data. The research results show that the Sultan Hasanudin – KH. Abdul Ghoni, in the aspect of road equipment facilities, there are 7 road equipment facilities in a damaged condition, in the aspect of the level of road unevenness in the medium category it has a percentage of 45% of the total length of the section, and for the aspect of the transverse slope on the Jl. Sultan Hasanuddin – KH. Abdul Ghoni has not met the standard for the transverse slope of asphalt pavement. Improved safety on the Jl. Sultan Hasanudin carried out further handling and improvements to road equipment and road pavement facilities, so that the Jl. Sultan Hasanuddin – KH. Abdul Ghoni does not have the potential to cause traffic accidents due to deficiencies in road infrastructure or dangerous road conditions.

Sufficient conditions for error distance reduction in the [formula omitted]-norm trust region between minimizers of local nonconvex multivariate quadratic approximates

This paper analyzes the sufficient conditions for distance reduction between minimizers of local nonconvex quadratic approximate functions with diagonal Hessian in the ℓ2-norm trust regions after two iterations. Some examples illustrate the theoretical results of this study.

Multimodal abnormalities of brain structures in adolescents and young adults with major depressive disorder: An activation likelihood estimation meta-analysis.

Major depressive disorder (MDD) in adolescents and young adults contributes significantly to global morbidity, with inconsistent findings on brain structural changes from structural magnetic resonance imaging studies. Activation likelihood estimation (ALE) offers a method to synthesize these diverse findings and identify consistent brain anomalies. To identify consistent brain structural changes in adolescents and young adults with MDD using ALE meta-analysis. We performed a comprehensive literature search in PubMed, Web of Science, Embase, and Chinese National Knowledge Infrastructure databases for neuroimaging studies on MDD among adolescents and young adults published up to November 19, 2023. Two independent researchers performed the study selection, quality assessment, and data extraction. The ALE technique was employed to synthesize findings on localized brain function anomalies in MDD patients, which was supplemented by sensitivity analyses. Twenty-two studies comprising fourteen diffusion tensor imaging (DTI) studies and eight voxel-based morphometry (VBM) studies, and involving 451 MDD patients and 465 healthy controls (HCs) for DTI and 664 MDD patients and 946 HCs for VBM, were included. DTI-based ALE demonstrated significant reductions in fractional anisotropy (FA) values in the right caudate head, right insula, and right lentiform nucleus putamen in adolescents and young adults with MDD compared to HCs, with no regions exhibiting increased FA values. VBM-based ALE did not demonstrate significant alterations in gray matter volume. Sensitivity analyses highlighted consistent findings in the right caudate head (11 of 14 analyses), right insula (10 of 14 analyses), and right lentiform nucleus putamen (11 of 14 analyses). Structural alterations in the right caudate head, right insula, and right lentiform nucleus putamen in young MDD patients may contribute to its recurrent nature, offering insights for targeted therapies.

Vacancy-Induced Anionic Electrons in Single-Metal Oxides and Their Possible Applications in Ammonia Synthesis.

Realizating of a low work function (WF) and room-temperature stability in electrides is highly desired for various applications, such as electron emitters, catalysts, and ion batteries. Herein, a criterion based on the electron localization function (ELF) and projected density of states (PDOS) in the vacancy of the oxide electride [Ca24Al28O64]4+(4e-) (C12A7) was adopted to screen out 13 electrides in single-metal oxides. By creating oxygen vacancies in nonelectride oxides, we find out 9 of them showed vacancy-induced anionic electrons. Considering the thermodynamic stability, two electrides with ordered vacancies, Nb3O3 and Ce4O3, stand out and show vacancy-induced zero-dimensional anionic electrons. Both exhibit low WFs, namely 3.1 and 2.3 eV for Nb3O3 and Ce4O3, respectively. In the case of Nb3O3, the ELF at oxygen vacancies decreases first and then increases during the decrease in the total number of electrons in self-consistent calculations due to Nb's multivalent state. Meanwhile, Ce4O3 displays promise for ammonia synthesis due to its low hydrogen diffusion barrier and low activation energy. Further calculations revealed that CeO with disordered vacancies at low concentrations also exhibits electride-like properties, suggesting its potential as a substitute for Ce4O3.

Structural Evolution of Small-Sized Phosphorus-Doped Boron Clusters: A Half-Sandwich-Structured PB15 Cluster.

The present study is a theoretical investigation into the structural evolution, electronic properties, and photoelectron spectra of phosphorus-doped boron clusters PBn0/- (n = 3-17). The results of this study revealed that the lowest energy structures of PBn- (n = 3-17) clusters, except for PB17-, exhibit planar or quasi-planar structures. The lowest energy structures of PBn (n = 3-17), with the exceptions of PB7, PB9, and PB15, are planar or quasi-planar. The ground state of PB7 has an umbrella-shaped structure, with C6V symmetry. Interestingly, the neutral cluster PB15 has a half-sandwich-like structure, in which the P atom is attached to three B atoms at one end of the sandwich, exhibiting excellent relative and chemical stability due to its higher second-order energy difference and larger HOMO-LUMO energy gap of 4.31 eV. Subsequently, adaptive natural density partitioning (AdNDP) and electron localization function (ELF) analyses demonstrate the bonding characteristics of PB7 and PB15, providing support for the validity of their stability. The calculated photoelectron spectra show distinct characteristic peaks of PBn- (n = 3-17) clusters, thus providing theoretical evidence for the future identification of doped boron clusters. In summary, our work has significant implications for understanding the structural evolution of doped boron clusters PBn0/- (n = 3-17), motivating further experiments regarding doped boron clusters.

Covalent Triazine Based Frameworks with Donor-Donor-π-Acceptor Structures for Dendrite-Free Lithium Metal Batteries.

The appearance of disordered lithium dendrites and fragile solid electrolyte interfaces (SEI) significantly hinder the serviceability of lithium metal batteries. Herein, guided by theoretical predictions, a multi-component covalent triazine framework with partially electronegative channels (4C-TA0.5TF0.5-CTF) is incorporated as a protective layer to modulate the interface stability of the lithium metal batteries. Notably, the 4C-TA0.5TF0.5-CTF with optimized electronic structure at the molecular level by fine-tuning the local acceptor-donor functionalities not only enhances the intermolecular interaction thereby providing larger dipole moment and improved crystallinity and mechanical stress, but also facilitates the beneficial effect of lithiophilic sites (C-F bonds, triazine cores, C=N linkages and aromatic rings) to further regulate the migration of Li+ and achieve a uniform lithium deposition behavior as determined by various in-depth in/ex situ characterizations. Due to the synergistic effect of multi-component organic functionalities, the 4C-TA0.5TF0.5-CTF modified full cells perform significantly better than the common two/three-component 2C-TA-CTF and 3C-TF-CTF electrodes, delivering an excellent capacity of 116.3 mAh g-1 (capacity retention ratio: 86.8 %) after 1000 cycles at 5 C and improved rate capability. This work lays a platform for the prospective molecular design of improved organic framework relative artificial SEI for highly stable lithium metal batteries.

Efficient Scheme for the Economic Heston–Hull–White Problem Using Novel RBF-FD Coefficients Derived from Multiquadric Function Integrals

This study presents an efficient method using the local radial basis function finite difference scheme (RBF-FD). The innovative coefficients are derived from the integrals of the multiquadric (MQ) function. Theoretical convergence rates for the coefficients used in function derivative approximation are provided. The proposed scheme utilizes RBF-FD estimations on three-point non-uniform stencils to construct the final approximation on a tensor grid for the 3D Heston–Hull–White (HHW) PDE, which is relevant in economics and mathematical finance. Numerical evidence and comparative analyses validate the results and the proposed scheme.

Chemically Accurate Singlet-Triplet Gaps of Arylcarbenes from Local Hybrid Density Functionals.

Singlet-triplet (ST) gaps are key descriptors of carbenes, because their properties and reactivity are strongly spin-dependent. However, the theoretical prediction of ST gaps is challenging and generally thought to require elaborate correlated wave function methods or double-hybrid density functionals. By evaluating two recent test sets of arylcarbenes (AC12 and AC18), we show that local hybrid functionals based on the "common t" local mixing function (LMF) model achieve mean absolute errors below 1 kcal/mol at a computational cost only slightly higher than that of global hybrid functionals. An analysis of correlation contributions to the ST gaps suggests that the accuracy of the common t-LMF model is mainly due to an improved description of nondynamical correlation which, unlike exchange, is not additive in each spin-channel. Although spin-nonadditivity can be achieved using the local spin polarization alone, using the "common", i.e., spin-unresolved, iso-orbital indicator t for constructing the LMF is found to be critical for consistent accuracy in ST gaps of arylcarbenes. The results support the view of LHs as vehicles to improve the description of nondynamical correlation rather than sophisticated exchange mixing approaches.

Current Indications and Future Direction in Heat Therapy for Musculoskeletal Pain: A Narrative Review

Background: Musculoskeletal pain is a non-negligible multifaceted condition affecting more than 30% of the global population. Superficial heat therapy (HT), through increasing tissue temperatures, plays a role in increasing local metabolism and function and relieving pain. Knee (KP) and sports pain represent two relevant fields of superficial HT application. Methods: In the present paper, a panel of experts performed a narrative review of the literature regarding the role of superficial HT in the management of knee and sports activity-related pain. Results: According to the reviewed literature, HT represents a therapeutic option in the management of musculoskeletal pain due to three main effects: pain relief, promotion of healing, and return to normal function and activity. Moreover, HT plays a role in sport activities both before and after exercise. Before performing sports, HT helps in preparing muscles for performance. After performing sports, it is capable to promote recovery and healing pathways. Combining and sequencing superficial heat and cold therapy represent an interesting topic of study. Overall, the application of heat wraps for superficial HT can be considered safe. Conclusions: HT has been shown to be a potentially beneficial and safe option in the management of several conditions including KP and sports. The key in the application of superficial HT is a multimodal and multidisciplinary approach.

Sharp Semiclassical Spectral Asymptotics for Local Magnetic Schrödinger Operators on $${\mathbb {R}}^d$$ Without Full Regularity

AbstractWe consider operators acting in $$L^2({\mathbb {R}}^d)$$ L 2 ( R d ) with $$d\ge 3$$ d ≥ 3 that locally behave as a magnetic Schrödinger operator. For the magnetic Schrödinger operators, we suppose the magnetic potentials are smooth and the electric potential is five times differentiable and the fifth derivatives are Hölder continuous. Under these assumptions, we establish sharp spectral asymptotics for localised counting functions and Riesz means.

First-principles investigation of positively charged and neutral oxygen vacancies in amorphous silica.

The structural parameters, electron localization functions, electron paramagnetic resonance (EPR) parameters, formation energies, and thermodynamic transition levels of various oxygen vacancy defects in amorphous silica are comprehensively and integrally investigated by using density functional theory. The trends of changes in the oxygen vacancy defect structure and electron localization induced by the increase in distance between defective silicon atoms are clearly identified. It is shown that the dimer configuration may be the potential structure of the Eδ' center. For the back-projected unpuckered configuration and the puckered configuration, whose EPR parameters are more consistent with the experimental values of the Eγ' center, the unpaired electron localized on the sp3 hybridized silicon atom is a common feature. Due to the three-coordinated oxygen atom in the forward-oriented configuration, the EPR parameters are closest to those of the Eα' center. Transformations of oxygen vacancy defects under different charge states are studied by sequentially adding and removing electrons. The thermodynamic transition level analysis reveals that the dimer and forward configurations may behave as deep traps for electron accumulation. The back-projected puckered fourfold-coordinated and fivefold-coordinated configurations are comparatively stable and may be able to function as shallow traps for electron transport. The neutral double unpuckered, neutral back-projected puckered fourfold-coordinated, and neutral back-projected unpuckered configurations are more likely to lose electrons during hole trapping. As the bias voltage is repeatedly changed, the defect density of the puckered configuration may reduce, while that of the dimer and unpuckered configuration may take an opposite trend.

Both the ionic and covalent bonds stabilize the W@Si12 cluster

Si is an important semiconductor material in the development of modern industry. With the miniaturization trend of semiconductor devices, the size of Si has reached the cluster size. The search for stable Si clusters is an important issue. In this work, the electronic structures and stability mechanism of the W@Si12 cluster are calculated by the first-principle calculations. Different from a C2v hexacapped trigonal prism structure of Si12, the W@Si12 cluster presents an embedded hexagonal prism structure with D6h symmetry. The addition of W atom leads to a higher stability. The molecular orbitals show obvious superatomic characteristics for the W@Si12 cluster, and their energy levels are more degenerate than that of the Si12 cluster. The population analysis indicates that a total charge of 2.21e is transferred from Si atoms to the center W atom, which suggests an ionic bond for W-Si. The electron localization function further proves a covalent bond for Si–Si. The enhanced stability of the W@Si12 cluster is attributed to the combination of the ionic and covalent bonds.

Quantum chemical investigations, Hirschfeld surface analysis, FMO, MESP, topology analyses, in-silico analysis and pharmacokinetics properties of 3-chloro-N-(4-hydroxy-3-methoxy-benzyl)-2,2-dimethyl propanamide [CHMBDP]

This article reports a comprehensive theoretical investigation of 3-chloro-n-(4-Hydroxy-3-Methoxy-Benzyl)-2,2-Dimethyl Propenamide (CHMBDP). Hirshfeld surface analysis provided a detailed visualization of intermolecular interactions within the crystal structure of CHMBDP. Analyses of Molecular Electrostatic Potential (MESP), Electron Localization Function (ELF), Localized Orbital Locator (LOL), and Reduced Density Gradient (RDG) offered insights into the compound’s reactivity and stability. The energies of the Highest Occupied Molecular Orbital (HOMO) and the Lowest Unoccupied Molecular Orbital (LUMO) indicated significant charge transfer within the molecule. In-silico analysis explored the compound’s interactions with TRPV1 (Transient Receptor Potential Vanilloid subtype 1), DNA, and BSA (Bovine Serum Albumin). The pharmacokinetic properties of CHMBDP were assessed using the Swiss ADME online tool to interpret its ADMET (Absorption, Distribution, Metabolism, Excretion, and Toxicity) characteristics. Overall, this study presents a thorough computational investigation of CHMBDP, characterizing its structure, properties, and potential applications.

Metal-Induced Enhancement of Tetrel Bonding. The Case of C⋅⋅⋅X-IrIII (X=Cl, Br) Tetrel Bond Involving a Methyl Group.

In X-ray structures of the isomorphic mer-[IrX3(THT)(CNXyl)2] (X=Cl 1, Br 2; THT=tetrahydrothiophene; Xyl=2,6-Me2C6H3-) complexes, we revealed short intermolecular contacts between the C-atom of an isocyanide methyl group and halide ligands of another molecule. Geometrical consideration of the X-ray data and analysis of appropriate DFT studies allowed the attribution of these contacts to CMe⋅⋅⋅X-IrIII (X=Cl, Br) tetrel bond. Specifically, through the application of DFT calculations and various theoretical models, the presence of tetrel bonding interactions was validated, and the contribution of the CMe⋅⋅⋅X-IrIII interaction was assessed. The reinforcement of the tetrel bond upon the isocyanide coordination to iridium(III) is substantiated by molecular electrostatic potential (MEP) surface calculations. To distinguish the tetrel bonding characteristics of CMe⋅⋅⋅X-IrIII (X=Cl, Br) interactions from conventional hydrogen bonding, we employed multiple computational methodologies, including Natural Bond Orbital (NBO) analysis and Electron Localization Function (ELF) analysis. Additionally, Energy Decomposition Analysis (EDA) was applied to selected model systems to explore the underlying physical nature of these interactions.

‘What we found is’

Abstract This paper examines two variants of the pseudo-cleft construction which display a WHAT-NP-VP-be pattern with the VP realised with cognitive verbs and the proform do in the context of spoken British English dyadic and multi-party BBC podcasts. It is based on the premise that the construction’s referencing potentials are both cataphoric and projective, and that depending on its contexts, one of the two referencing functions is foregrounded while the other is backgrounded. The analysis focuses on those linguistic features and contextual configurations which either contribute to its cataphoric referencing function, or which go beyond the local cataphoric referencing function and indicate its projective, discourse-organising function. The research is corpus-based and uses quantitative and qualitative methodologies, filtering out the linguistic features and contextual configurations which contribute to assigning the two variants the status of a projective construction with a discourse-organising function. The features under investigation are (1) the semantics of the constitutive NPs and VPs marking for tense, aspect and modality and their uptake in the discourse, (2) degrees of continuity and discontinuity in the cohesive chains triggered by the constitutive parts of the construction. The paper shows that when semantic continuity between the what-clause and what follows is discontinued and thus deferred, the construction’s projective function is foregrounded.

General Shiba mapping for on-site four-point correlation functions

By applying the Shiba mapping on the two-particle level, we derive the relation between the local four-point correlation functions of bipartite lattice models with on-site electronic repulsion and those of the corresponding models with attractive interaction in the most general setting. In particular, we extend the results of [], which were limited to the rather specific situation of the static limit in strictly particle-hole symmetric models, (i) by explicitly including magnetic field and different values of the chemical potentials, and (ii) by considering the full dependence of the generalized susceptibilities on the transfer (bosonic) Matsubara frequency. The derived formalism is then applied, as a relevant benchmark, to the Hubbard atom by investigating the general properties of the divergences of its irreducible vertex functions as a function of chemical potential and applied magnetic field. The resulting phase diagrams provide an insightful compass for future studies of the breakdown of the self-consistent perturbation expansion beyond high-symmetric regimes. Published by the American Physical Society 2024

Effects of Mg and Al doping on the desorption energetics and electronic structure of a Ti-V-Zr-Nb alloy hydride

Refractory high-entropy alloys (HEAs) show promise for novel hydrogen storage technology, but addressing their limited gravimetric hydrogen storage capacity necessitates exploration of light alloying elements including Mg and Al. Here, we employ density-functional theory to investigate the hydrogen desorption energetics of Ti0.325V0.275Zr0.125Nb0.275 alloy and the impact of doping with Mg and Al. Our analysis reveals that Mg and Al addition thermodynamically destabilize the Ti0.325V0.275Zr0.125Nb0.275-hydride and lower its storage capacity. The observed destabilization is attributed to reduced chemical contributions to the desorption enthalpy in the Mg and Al-doped hydrides. Detailed examination of the electronic density of states, electron localization function, and crystal orbital Hamilton population analysis unveils fundamental features of chemical bonding in these hydrides. Notably, H-H antibonding states occur for hydrogen atoms located in the nearest-neighbor interstices of Mg and Al atoms. Charge transfer facilitates formation of these antibonding states. This comprehensive analysis enhances our understanding of the intricate interplay between electronic structure, hydrogen desorption energetics, and chemical bonding in HEA hydrides, offering valuable insights for the design and optimization of advanced hydrogen storage materials.