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As a precursor to various reactive nitrogen species formed in biological systems, nitric oxide (•NO) participates in numerous processes, including enhancing DNA radiosensitivity in ionizing radiation-based radiotherapy. Forming guanine radical cations is another common DNA lesion resulting from ionization and oxidation damage. As such, the interaction of •NO with guanine radical cations (G•+) may contribute to the radiosensitization of •NO. An intriguing aspect of this process is the participation of multiple spin configurations in the reaction, including open-shell singlet 1,OS[G•+(↑)⋯(↓)•NO], closed-shell singlet 1,CS[G(↑↓)⋯NO+], and triplet 3[G•+(↑)⋯(↑)•NO]. In this study, the reactions of •NO with both unsubstituted guanine radical cations (in the 9HG•+ conformation) and 9-methylguanine radical cations (9MG•+, a guanosine-mimicking model compound) were investigated in the absence and presence of monohydration of radical cations. Kinetic-energy dependent reaction product ions and cross sections were measured using an electrospray ionization guided-ion beam tandem mass spectrometer. The reaction mechanisms, kinetics, and dynamics were comprehended by interpreting the reaction potential energy surface using spin-projected density functional theory, coupled cluster theory, and multiconfiguration complete active space second-order perturbation theory, followed by RRKM kinetics modeling. The combined experimental and computational findings revealed closed-shell singlet 1,CS[7-NO-9MG]+ as the major, exothermic product and triplet 3[8-NO-9MG]+ as the minor, endothermic product. Singlet biradical products were not detected due to high reaction endothermicities, activation barriers, and inherent instability. [ABSTRACT FROM AUTHOR]

Using size-selected anion photoelectron spectroscopy and density functional theory, we investigated the structures and properties of fluorinated bimetallic clusters CoAuF1-2− and CuAuF1-2− and their neutrals. Both experimental and theoretical results show that in these cluster anions, Au behaves like a halogen atom. For example, the measured vertical detachment energies (VDEs) of CoAuF− (2.00 ± 0.08 eV) and CuAuF− (3.8 ± 0.1 eV) are close to those of CoF2− (2.12 ± 0.08 eV) and CuF2− (3.58 ± 0.08 eV), respectively. The theoretical results show that the geometries and electronic structures of CoAuF− and CuAuF− are similar to those of CoF2− and CuF2−. The natural population analysis and natural electron configuration analyses further confirm that the electronic properties of Au in MAuF− (M = Co, Cu) mimic those of MF2−. In addition, the electron localization function analyses show that the M-Au chemical bonds are similar to the corresponding M-F chemical bonds, providing evidence for the ionic nature of the interactions. When a second F atom is attached to the CoAuF− and CuAuF− clusters, the VDEs of the resulting CoAuF2− and CuAuF2− are 4.38 ± 0.08 eV and 3.71 ± 0.08 eV, respectively, indicating their superhalogen character as these values are higher than those of halogen anions. The results may be useful for understanding the properties of gold at the nanoscale that play an important role in catalysis and nanotechnology. [ABSTRACT FROM AUTHOR]

We have recently introduced an original method for sharply partitioning the correlation energy into dynamic and non-dynamic contributions. This method is based on the node of the Hartree–Fock (HF) Slater determinant and the stochastic projector fixed-node diffusion Monte Carlo (FNDMC) method [Šulka et al., J. Chem. Theory Comput. 19, 8147 (2023)]. This approach addresses the challenge of dissecting correlation energy in quantum chemistry. Here, we present the first application of this technique to explore CASSCF correlation energy contributions in selected molecular systems such as BH, FH, F2, and H2–H2. The results show that correlation energies derived from the full-valence active space CASSCF method, often believed to describe mostly non-dynamic correlation effects, contain an extraneous, unwanted, system-dependent component that belongs to the dynamic correlation energy. The findings suggest that the new HF-node/FNDMC-based electron correlation energy decomposition method provides a useful complementary tool, enabling the detection of inherent challenges in distinguishing between dynamic and non-dynamic contributions to correlation energies within methods where precise dissection of these effects is not possible. [ABSTRACT FROM AUTHOR]

We propose introducing an extended Hubbard Hamiltonian derived via the ab initio downfolding method, which was originally formulated for periodic materials, toward efficient quantum computing of molecular electronic structure calculations. By utilizing this method, the first-principles Hamiltonian of chemical systems can be coarse-grained by eliminating the electronic degrees of freedom in higher energy space and reducing the number of terms of electron repulsion integral from O ( N 4 ) to O ( N 2 ). Our approach is validated numerically on the vertical excitation energies and excitation characters of ethylene, butadiene, and hexatriene. The dynamical electron correlation is incorporated within the framework of the constrained random phase approximation in advance of quantum computations, and the constructed models capture the trend of experimental and high-level quantum chemical calculation results. As expected, the L1-norm of the fermion-to-qubit mapped model Hamiltonians is significantly lower than that of conventional ab initio Hamiltonians, suggesting improved scalability of quantum computing. Those numerical outcomes and the results of the simulation of excited-state sampling demonstrate that the ab initio extended Hubbard Hamiltonian may hold significant potential for quantum chemical calculations using quantum computers. [ABSTRACT FROM AUTHOR]

The present work reports the effects of 120 MeV Au9+ on structural and electronic properties of polycrystalline SnO2 films of about 170 nm thickness prepared by spin-coating. 119Sn Mössbauer measurements are used to probe the electronic properties. The observed isomer-shift values clearly indicate Sn4+ for the pristine sample and its progressive reduction to Sn2+ and eventually to the metallic Sn state at higher fluence values. These observations are corroborated by x-ray diffraction, Raman, and x-ray photo-electron spectroscopy measurements. The x-ray diffraction measurements indicate the complete amorphization of the tin oxide phase, while the recrystallization of the metallic Sn phase with irradiation. The optical bandgap is observed to vary with ion beam irradiation. The observations indicate the possibility of tuning the electronic configuration of Sn in tin oxide thin films with swift heavy ion beam irradiation, and the results are explained in terms of the thermal-spike model of swift heavy ion irradiation. [ABSTRACT FROM AUTHOR]

The doping of CdS quantum dots (QDs) with Cu(I) disrupts electron–hole correlation due to hole trapping by the dopant ion, post-photoexcitation. The present paper examines the effect of such disruption on the rate of photoinduced electron transfer (PET) from the QDs to methyl viologen (MV2+), with implications in their photocatalytic activity. A significantly greater efficiency of PL quenching by MV2+ is observed for the doped QDs than for the undoped ones. Interestingly, the Stern–Volmer plots constructed using PL intensities exhibit an upward curvature for both the cases, while the PL lifetimes remain unaffected. This observation is rationalized by considering the adsorption of the quencher on the surface of the QDs and ultrafast PET post-photoexcitation. Ultrafast transient absorption experiments confirm a faster electron transfer for the doped QDs. It is also realized that the transient absorption experiment yields a more accurate estimate of the binding constant of the quencher with the QDs, than the PL experiment. [ABSTRACT FROM AUTHOR]

The ultrafast relaxation dynamics of tetracene following UV excitation to the bright singlet state S6 has been studied with time-resolved photoelectron spectroscopy. With the help of high-level ab initio multireference perturbation theory calculations, we assign photoelectron signals to intermediate dark electronic states S3, S4, and S5 as well as to a low-lying electronic state S2. The energetic structure of these dark states has not been determined experimentally previously. The time-dependent photoelectron yields assigned to the states S6, S5, and S4 have been analyzed and reveal the depopulation of S6 within 60 fs, while S5 and S4 are populated with delays of about 50 and 80 fs. The dynamics of the lower-lying states S3 and S2 seem to agree with a delayed population coinciding with the depopulation of the higher-lying states S4–S6 but could not be elucidated in full detail due to the low signal levels of the corresponding two-photon ionization probe processes. [ABSTRACT FROM AUTHOR]

We show that optimal control of the electron dynamics is able to prepare molecular ground states, within chemical accuracy, with evolution times approaching the bounds imposed by quantum mechanics. We propose a specific parameterization of the molecular evolution only in terms of interaction already present in the molecular Hamiltonian. Thus, the proposed method solely utilizes quantum simulation routines, retaining their favorable scalings. Due to the intimate relationships between variational quantum algorithms and optimal control, we compare, when possible, our results with state-of-the-art methods in the literature. We found that the number of parameters needed to reach chemical accuracy and algorithmic scaling is in line with compact adaptive strategies to build variational Ansätze. The algorithm, which is also suitable for quantum simulators, is implemented by emulating a digital quantum processor (up to 16 qubits) and tested on different molecules and geometries spanning different degrees of electron correlation. [ABSTRACT FROM AUTHOR]

Zr-based MXenes recently attracted attention because of its experimental preparation showing temperature stability, mechanical strength, and promising energy, sensoric, and electrochemistry applications. However, necessary theoretical predictions at a precise/predictive level are complicated due to essential excitonic features and strong electron correlation (i.e., a necessity to go beyond standard density functional theory, DFT). Contrary to the prevailing focus on oxygen-terminated MXenes and standard predictions of other Zr-based MXenes as conductors, based on the hybrid DFT and GW many-body perturbational theory, we were able to find seven different semiconductors (five of them for their equilibrium geometry and two others under slight tensile biaxial strain) in the case of two- and three-layered Z r 2 C T 2 and Z r 3 C 2 T 2 configurations with various terminations (T = O, F, S, Cl). We observed semiconductor-to-conductor transition induced by strain in the majority of such Zr-based MXenes at an experimentally achievable strain range. Furthermore, using the Bethe–Salpeter equation (BSE), we demonstrated that selected semiconducting Zr-based MXenes possess high optical absorption efficiency (20%–30%) in the visible light range, underscoring their potential in photonic applications. The high sensitivity of Zr-based MXenes to external conditions and functionalization combined with the thermal stability makes the materials promising for applications at operational temperatures in electronic and optical technologies. [ABSTRACT FROM AUTHOR]

Nanoscale semiconductors with isolated spin impurities have been touted as promising materials for their potential use at the intersection of quantum, spin, and information technologies. Electron paramagnetic resonance (EPR) studies of spins in semiconducting carbon nanotubes have overwhelmingly focused on spins more strongly localized by sp3-type lattice defects. However, the creation of such impurities is irreversible and requires specific reactions to generate them. Shallow charge impurities, on the other hand, are more readily and widely produced by simple redox chemistry, but have not yet been investigated for their spin properties. Here, we use EPR to study p-doped (6,5) semiconducting single-wall carbon nanotubes (s-SWNTs) and elucidate the role of impurity–impurity interactions in conjunction with exchange and correlation effects for the spin behavior of this material. A quantitative comparison of the EPR signals with phenomenological modeling combined with configuration interaction electronic structure calculations of impurity pairs shows that orbital overlap, combined with exchange and correlation effects, causes the EPR signal to disappear due to spin entanglement for doping levels corresponding to impurity spacings of 14 nm (at 30 K). This transition is predicted to shift to higher doping levels with increasing temperature and to lower levels with increasing screening, providing an opportunity for improved spin control in doped s-SWNTs. [ABSTRACT FROM AUTHOR]

We performed high-level ab initio quantum chemical calculations, incorporating higher-order excitations, spin–orbit coupling (SOC), and the Gaunt interaction, to calculate the electron affinities (EAs) of alkaline earth (AE) metal atoms (Ca, Sr, Ba, and Ra), which are notably small. The coupled-cluster singles and doubles with perturbative triples [CCSD(T)] method is insufficient to accurately calculate the EAs of AE metal atoms. Higher-order excitations proved crucial, with the coupled-cluster singles, doubles, and triples with perturbative quadruples [CCSDT(2)Q] method effectively capturing dynamic electron correlation effects. The contributions of SOC (ΔESOs) to the EAs calculated using the multireference configuration interaction method with the Davidson correction, including SOC, positively enhance the EAs; however, these contributions are overestimated. The Dirac–Hartree–Fock (DHF)-CCSD(T) method addresses this overestimation and provides reasonable values for ΔESO (ΔESO−D). Employing additional sets of diffuse and core–valence correlation basis sets is critical for accurately calculating the EAs of AE metal atoms. The contributions of the Gaunt interaction (ΔEGaunt) to the EAs of AE metal atoms are negligible. Notably, the CCSDT(2)Q with the complete basis set limit + ΔESO−D + ΔEGaunt produced EA values for Ca, Sr, and Ba that closely aligned with experimental data and achieved accuracy exceeding the chemical accuracy. Based on our findings, the accurately proposed EA for Ra is 9.88 kJ/mol. [ABSTRACT FROM AUTHOR]

We find that the unit cell volume (V), which affects many properties, decreases too rapidly with strain when calculated with standard density functional theories (DFTs) such as local density approximation (LDA). We find that this demerit is moderated with the use of the Hubbard potential U for local electron correlation (DFT + U). However, the introduction of U to standard DFTs, e.g., LDA and Perdew–Burke–Ernzerhof functional (PBE) optimized for solids (PBEsol), leads to the excessive underestimation of the spontaneous polarization (PS) and frequently extinguishes PS. Therefore, we attempt to improve the overall accuracy of DFTs for ferroelectrics by using U in several DFT methods including PBE that overestimates PS and lattice constants. We demonstrate that PBE with U (PBE + U) is in excellent agreement with the experimental properties of BaTiO3 and SrTiO3, with improvements in the estimates of lattice constants, PS, the phonon frequency, the antiferrodistortive angle of 105 K-phase SrTiO3, the bandgap, the strain dependence of V, and hole polarons. When the lattice parameters and PS moderately agree with the experimental data, PBE + U with a single U set can produce both electron and hole polarons. Hence, PBE + U can be a practical substitute of hybrid functionals for perovskite oxide ferroelectrics, except for the estimation of the bandgap. Furthermore, we propose an approach to construct a functional accurately depicting the incipient ferroelectric state of SrTiO3. Additionally, these results suggest that conventional DFT underestimates PS under compressive in-plane strain and predicts the unrealistic deformation of ferroelectrics and that in-plane-strained lattices can mitigate the problems associated with U. [ABSTRACT FROM AUTHOR]

We propose an efficient version of ensemble Hartree–Fock/density functional theory to calculate a set of two charge-transfer states for systems with odd-numbers of electrons. The approach does require definitions of donor/acceptor fragments; however, the approach is not very sensitive to such definitions—even in the limit of very strong electronic coupling. The key ansatz is that, by mandating that the vector space spanned by the active orbitals projects equally onto the donor and acceptor fragments, such a constraint eliminates all intra-molecular local excitations and makes it far easier to generate potential energy surfaces that are smooth over a wide region of configuration space. The method is fast, working with only two electron configurations, and should be useful for ab initio non-adiabatic dynamics in the near future. [ABSTRACT FROM AUTHOR]

A major difficulty in quantum simulation is the adequate treatment of a large collection of entangled particles, synonymous with electron correlation in electronic structure theory, with coupled cluster (CC) theory being the leading framework for dealing with this problem. Augmenting computationally affordable low-rank approximations in CC theory with a perturbative account of higher-rank excitations is a tractable and effective way of accounting for the missing electron correlation in those approximations. This is perhaps best exemplified by the "gold standard" CCSD(T) method, which bolsters the baseline CCSD with the effects of triple excitations using considerations from many-body perturbation theory (MBPT). Despite this established success, such a synergy between MBPT and the unitary analog of CC theory (UCC) has not been explored. In this work, we propose a similar approach wherein converged UCCSD amplitudes are leveraged to evaluate energy corrections associated with triple excitations, leading to the UCCSD[T] method. In terms of quantum computing, this correction represents an entirely classical post-processing step that improves the energy estimate by accounting for triple excitation effects without necessitating new quantum algorithm developments or increasing demand for quantum resources. The rationale behind this choice is shown to be rigorous by studying the properties of finite-order UCC energy functionals, and our efforts do not support the addition of the fifth-order contributions as in the (T) correction. We assess the performance of these approaches on a collection of small molecules and demonstrate the benefits of harnessing the inherent synergy between MBPT and UCC theories. [ABSTRACT FROM AUTHOR]

In the past decade, natural orbital functional (NOF) approximations have emerged as prominent tools for characterizing electron correlation. Despite their effectiveness, these approaches, which rely on natural orbitals and their associated occupation numbers, often require hybridization with other methods to fully account for all correlation effects. Recently, a global NOF (GNOF) has been proposed [Piris, Phys. Rev. Lett. 127, 233001 (2021)] to comprehensively address both dynamic and static correlations. This study evaluates the performance of GNOF on strongly correlated model systems, including comparisons with highly accurate Full Configuration Interaction calculations for hydrogen atom clusters in one, two, and three dimensions. Additionally, the investigation extends to a BeH2 reaction, involving the insertion of a beryllium atom into a hydrogen molecule along a C2v pathway. According to the results obtained using GNOF, consistent behavior is observed across various correlation regions, encompassing a range of occupations and orbital schemes. Furthermore, distinctive features are identified when varying the dimensionality of the system. [ABSTRACT FROM AUTHOR]

Algebraic diagrammatic construction (ADC) is a computationally efficient approach for simulating excited electronic states, absorption spectra, and electron correlation. Due to their origin in perturbation theory, the single-reference ADC methods may be susceptible to spin contamination when applied to molecules with unpaired electrons. In this work, we develop an approach to quantify spin contamination in the ADC calculations of electronic excitations and apply it to a variety of open-shell molecules starting with either the unrestricted (UHF) or restricted open-shell (ROHF) Hartree–Fock reference wavefunctions. Our results show that the accuracy of low-order ADC approximations [ADC(2) and ADC(3)] significantly decreases when the UHF reference spin contamination exceeds 0.05 a.u. Such strongly spin-contaminated molecules exhibit severe excited-state spin symmetry breaking that contributes to decreasing the quality of computed excitation energies and oscillator strengths. In a case study of phenyl radical, we demonstrate that spin contamination can significantly affect the simulated UV/Vis spectra, altering the relative energies, intensities, and order of electronic transitions. The results presented here motivate the development of spin-adapted ADC methods for open-shell molecules. [ABSTRACT FROM AUTHOR]

We implanted Fe+ ions in nanodiamond (ND) powder containing negatively charged nitrogen-vacancy (NV−) centers and studied their Raman spectra and optically detected magnetic resonance (ODMR) in various applied magnetic fields with green light (532 nm) excitation. In Raman spectra, we observed a blue shift of the NV− peak associated with the conversion of the electronic sp3 configuration to the disordered sp2 one typical for the carbon/graphite structure. In the ODMR spectra, we observed a red shift of the resonance position caused by local heating by an absorptive environment that recovers after annealing. To reveal the red shift mechanism in ODMR, we created a controlled absorptive environment around ND by adding iron-based Fe2O3 and graphitic sp2 powders to the ND suspension. This admixture caused a substantial increase in the observed shift proportional to the applied laser power, corresponding to an increase in the local temperature by 150–180 K. This surprisingly large shift is absent in non-irradiated NV-ND powders, is associated only with the modification of the local temperature by the absorptive environment of NV-NDs, and can be studied using ODMR signals of NV−. [ABSTRACT FROM AUTHOR]

Using the density functional theory, we conducted a study on the electrification upon contact between hydrophobic liquid molecules and water molecules, revealing localized characteristics of contact-electrification. These "localized features" refer to the specific microscale characteristics where electron transfer predominantly occurs at the contact regions, influenced by factors such as atomic distances and molecular orientations. Although the electrostatic potential and the highest occupied molecular orbital–lowest unoccupied molecular orbital gap offer substantial predictive insights for electron transfer across polymer interfaces, they fall short in capturing the complexities associated with the interaction between hydrophobic liquids and water molecules. The electronegativity of elements at the interface and the localization of molecular orbitals play a decisive role in electron transfer. Simultaneously, for liquid molecules with irregular structures, there is no correlation between the "contact area" and the amount of electron transfer. The "contact area" refers to the surface region where two different liquid molecules come into close proximity. It is defined by the surface area of atoms with interatomic distances smaller than the van der Waals radius. This study challenges traditional assumptions about contact-electrification, particularly in liquid–liquid interfaces, providing new insights into the localized nature of this phenomenon. [ABSTRACT FROM AUTHOR]

Ceria (CeO2) doped with Gd2O3 (Ce1−xGdxO2−x/2) is considered a surrogate of a burnable poison-doped nuclear fuel. Oxygen vacancies (VO) are induced in Ce1−xGdxO2−x/2 by the substitution of Gd3+ ions into the Ce4+ sites, and the oxygen deficiency is mainly controlled by the Gd2O3 concentration. Oxygen vacancies can also be generated by elastic collisions with high-energy electrons for recoil energies of oxygen atoms above the threshold displacement energy (Ed,O). Oxygen vacancy formation is a key factor to determine the radiation tolerance since it enhances the recombination of point defects. The behavior of point defects in ceramics is known to depend on their charge states, although there is only limited research on this topic. In this study, in situ cathodoluminescence (CL) spectroscopy is applied to studying the charge states of defects induced in the oxygen-deficient cerium dioxides, Ce1−xGdxO2−x/2, by using a high-voltage electron microscope for electron energies from 400 to 1250 keV. The CL emission bands of Ce3+ − VO, Ce3+, and F+ centers are obtained for Ce1−xGdxO2−x/2 as well as pure ceria. An energy shift and quenching of CL emission in Ce1−xGdxO2−x/2 are observed. Those effects are discussed as a consequence of the generation of extrinsic oxygen vacancies induced by Gd2O3 doping (VO,ext) and the influence of the respective electronic configurations of the Ce3+ ions and VO,ext. A schematic picture of energy levels of defects in the bandgap of Ce1−xGdxO2−x/2 is suggested. [ABSTRACT FROM AUTHOR]

We present cross sections for the formation of positronium chloride (PsCl) in its ground state from the charge exchange between positronium (Ps) and chloride (Cl−) in the range of 10 meV–100 eV Ps energy. We have used theoretical models based on the first Born approximation in its three-body formulation. We simulated the collisions between Ps and Cl− using ab initio binding energies and positronic wave functions at both the mean-field and correlated levels extrapolated to the complete basis set limit. The accuracy of these ab initio data was benchmarked on the PsF system with the existing highly accurate results, including the very recent quantum Monte Carlo results. We have investigated Ps excited states up to n = 4. The results suggest that the channel Ps(n = 2) is of particular interest for the production of PsCl in the ground state and shows that an accurate treatment of correlation effects (i.e., electron–electron and electron–positron correlations) leads to a significant change in the magnitude of the PsCl production cross section with respect to the mean-field level. [ABSTRACT FROM AUTHOR]

We present cross sections for the formation of positronium chloride (PsCl) in its ground state from the charge exchange between positronium (Ps) and chloride (Cl−) in the range of 10 meV–100 eV Ps energy. We have used theoretical models based on the first Born approximation in its three-body formulation. We simulated the collisions between Ps and Cl− using ab initio binding energies and positronic wave functions at both the mean-field and correlated levels extrapolated to the complete basis set limit. The accuracy of these ab initio data was benchmarked on the PsF system with the existing highly accurate results, including the very recent quantum Monte Carlo results. We have investigated Ps excited states up to n = 4. The results suggest that the channel Ps(n = 2) is of particular interest for the production of PsCl in the ground state and shows that an accurate treatment of correlation effects (i.e., electron–electron and electron–positron correlations) leads to a significant change in the magnitude of the PsCl production cross section with respect to the mean-field level. [ABSTRACT FROM AUTHOR]

We develop and demonstrate how to use the Graphical Unitary Group Approach (GUGA)-based MRCISD with Core–Valence Separation (CVS) approximation to compute the core-excited states. First, perform a normal Self-Consistent-Field (SCF) or valence MCSCF calculation to optimize the molecular orbitals. Second, rotate the optimized target core orbitals and append to the active space, form an extended CVS active space, and perform a CVS-MCSCF calculation for core-excited states. Finally, construct the CVS-MRCISD expansion space and perform a CVS-MRCISD calculation to optimize the CI coefficients based on the variational method. The CVS approximation with GUGA-based methods can be implemented by flexible truncation of the Distinct Row Table. Eliminating the valence-excited configurations from the CVS-MRCISD expansion space can prevent variational collapse in the Davidson iteration diagonalization. The accuracy of the CVS-MRCISD scheme was investigated for excitation energies and compared with that of the CVS-MCSCF and CVS-CASPT2 methods using the same active space. The results show that CVS-MRCISD is capable of reproducing well-matched vertical core excitation energies that are consistent with experiments by combining large basis sets and a rational reference space. The calculation results also highlight the fact that the dynamic correlation between electrons makes an undeniable contribution in core-excited states. [ABSTRACT FROM AUTHOR]

Tailoring the crystal structure, spin, and charge state of perovskite oxides through fluorine ion doping is an attractive and effective strategy, which could significantly modify the physical and chemical properties of base oxides. Here, BaFe1−xMnxO3−δ (x = 0, 0.1, 0.2, 0.3) and BaFe1−xMnxO2.9−δF0.1 (x = 0.1, 0.2, 0.3), belonging to 6H-type BaFeO3−δ, are prepared and investigated to evaluate the impact of F− doping. The distortion of crystal structure and the reduced average valence of Mn and Fe confirm the preference for F− substitution in the hexagonal layer, which are found as the key factors for the improved magnetic properties, including ferromagnetic ordering temperature, coercive force, and remanent magnetization. Moreover, the valence reduction of B-site ions and the increased resistance distinctly indicate the expense of electron hole via fluorine doping. This work describes the adjustment of crystal structure, electronic configuration, and ferromagnetic performance by simple F− doping, which provides a prospect for practical magnetic materials. [ABSTRACT FROM AUTHOR]

Tailoring the crystal structure, spin, and charge state of perovskite oxides through fluorine ion doping is an attractive and effective strategy, which could significantly modify the physical and chemical properties of base oxides. Here, BaFe1−xMnxO3−δ (x = 0, 0.1, 0.2, 0.3) and BaFe1−xMnxO2.9−δF0.1 (x = 0.1, 0.2, 0.3), belonging to 6H-type BaFeO3−δ, are prepared and investigated to evaluate the impact of F− doping. The distortion of crystal structure and the reduced average valence of Mn and Fe confirm the preference for F− substitution in the hexagonal layer, which are found as the key factors for the improved magnetic properties, including ferromagnetic ordering temperature, coercive force, and remanent magnetization. Moreover, the valence reduction of B-site ions and the increased resistance distinctly indicate the expense of electron hole via fluorine doping. This work describes the adjustment of crystal structure, electronic configuration, and ferromagnetic performance by simple F− doping, which provides a prospect for practical magnetic materials. [ABSTRACT FROM AUTHOR]

Localized atomic orbitals are the preferred basis set choice for large-scale explicit correlated calculations, and high-quality hierarchical correlation-consistent basis sets are a prerequisite for correlated methods to deliver numerically reliable results. At present, numeric atom-centered orbital (NAO) basis sets with valence correlation consistency (VCC), designated as NAO-VCC-nZ, are only available for light elements from hydrogen (H) to argon (Ar) [Zhang et al., New J. Phys. 15, 123033 (2013)]. In this work, we extend this series by developing NAO-VCC-nZ basis sets for krypton (Kr), a prototypical element in the fourth row of the periodic table. We demonstrate that NAO-VCC-nZ basis sets facilitate the convergence of electronic total-energy calculations using the Random Phase Approximation (RPA), which can be used together with a two-point extrapolation scheme to approach the complete basis set limit. Notably, the Basis Set Superposition Error (BSSE) associated with the newly generated NAO basis sets is minimal, making them suitable for applications where BSSE correction is either cumbersome or impractical to do. After confirming the reliability of NAO basis sets for Kr, we proceed to calculate the Helmholtz free energy for Kr crystal at the theoretical level of RPA plus renormalized single excitation correction. From this, we derive the pressure–volume (P–V) diagram, which shows excellent agreement with the latest experimental data. Our work demonstrates the capability of correlation-consistent NAO basis sets for heavy elements, paving the way toward numerically reliable correlated calculations for bulk materials. [ABSTRACT FROM AUTHOR]

In density-functional theory, the exchange–correlation (XC) energy can be defined exactly through the coupling-constant (λ) averaged XC hole n ̄ xc (r , r ′ ) , representing the probability depletion of finding an electron at r′ due to an electron at r. Accurate knowledge of n ̄ xc (r , r ′ ) has been crucial for developing XC energy density-functional approximations and understanding their performance for molecules and materials. However, there are very few systems for which accurate XC holes have been calculated since this requires evaluating the one- and two-particle reduced density matrices for a reference wave function over a range of λ while the electron density remains fixed at the physical (λ = 1) density. Although the coupled-cluster singles and doubles (CCSD) method can yield exact results for a two-electron system in the complete basis set limit, it cannot capture the electron–electron cusp using finite basis sets. Focusing on Hooke's atom as a two-electron model system for which certain analytic solutions are known, we examine the effect of this cusp error on the XC hole calculated using CCSD. The Lieb functional is calculated at a range of coupling constants to determine the λ-integrated XC hole. Our results indicate that, for Hooke's atoms, the error introduced by the description of the electron–electron cusp using Gaussian basis sets at the CCSD level is negligible compared to the basis set incompleteness error. The system-, angle-, and coupling-constant-averaged XC holes are also calculated and provide a benchmark against which the Perdew–Burke–Ernzerhof and local density approximation XC hole models are assessed. [ABSTRACT FROM AUTHOR]

π-conjugated polymers have been used in a wide range of practical applications, partly due to their unique properties that originate in the delocalization of electrons through the polymer backbone. The level of delocalization can be characterized by the induced bond length alternation (BLA), with shorter BLA connected with strong delocalization and vice versa. The accurate description of this structural parameter can be considered a benchmark for testing the capability of different electronic structure methods for self-interaction error (SIE) removal and electron correlation inclusion. Density functional theory (DFT), in its local or semi-local flavors, suffers from SIE and, thus, underestimates the BLA compared to self-interaction-free methods. In this work, we utilize the Fermi–Löwdin orbital self-interaction correction (FLOSIC) method for one-electron self-interaction removal to characterize the BLA of five oligomers with increasing length extrapolated to the polymeric limit. We compare the self-interaction-free BLA to several DFT approximations, Møller–Plesset second-order perturbation theory (MP2), and the BLA obtained with the domain based local pair natural orbital CCSD(T) [DLPNO-CCSD(T)] approximation. Our findings show that FLOSIC corrects for the small BLA given by (semi-)local DFT approximations, but it tends to overcorrect with respect to CAM-B3LYP, MP2, and DLPNO-CCSD(T). [ABSTRACT FROM AUTHOR]

Although it plays a critical role in the photophysics and catalysis of lanthanides, spin–orbit coupling of electrons on individual lanthanide atoms in small clusters is not well understood. The major objective of this work is to probe such coupling of the praseodymium (Pr) 4f and 6s electrons in Pr2O2 and Pr2O2+. The approach combines mass-analyzed threshold ionization spectroscopy and spin–orbit multiconfiguration second-order quasi-degenerate perturbation theory. The energies of six ionization transitions are precisely measured; the adiabatic ionization energy of the neutral cluster is 38 045 (5) cm−1. Most of the electronic states involved in these transitions are identified as spin–orbit coupled states consisting of two or more electron spins. The electron configurations of these states are 4f46s2 for the neutral cluster and 4f46s for the singly charged cation, both in planar rhombus-type structures. The spin–orbit splitting due to the coupling of the electrons on the separate Pr atoms is on the order of hundreds of wavenumbers. [ABSTRACT FROM AUTHOR]

Parr and Ghosh [Phys. Rev. A. 51 3564 (1995)] demonstrated that when near-exact electron densities and potentials are used, the exchange–correlation energies of first- and second-row atoms are well-described by a combination of the Fermi–Amaldi functional with a functional that is homogeneous of degree one under density scaling. Insight into this observation is provided by considering their work from the perspective of the effective homogeneity of the overall exchange–correlation functional. By considering a general form that combines the Fermi–Amaldi functional with a functional that is homogeneous of degree k, it is shown that for these atoms, the functional of Parr and Ghosh (k = 1) exhibits essentially optimal effective homogeneities on the electron-deficient side of the integer. Percentage errors in effective homogeneities are close to percentage errors in exchange–correlation energies. [ABSTRACT FROM AUTHOR]

We investigate two limits in open-shell diradical systems: O3, in which the interesting orbitals are in close proximity to one another, and (C21H13)2, where there is a significant spatial separation between the two orbitals. In accord with earlier calculations, we find that standard density-functional approximations do not predict the open-shell character for the former case but uniformly predict the open-shell character for the latter case. We trace the qualitatively incorrect behavior in O3 predicted by these standard density functional approximations to self-interaction error and use the Fermi–Löwdin-orbital-self-interaction-corrected formalism to determine accurate triplet, closed-shell singlet, and open-shell broken-spin-symmetry electronic configurations. Analysis of the resulting many-electron overlap matrices allows us to unambiguously show that the broken-spin-symmetry configurations do not participate in the representation of the Ms = 0 triplet states and allows us to reliably extract the singlet–triplet splitting in O3 by analyzing the energy as a function of Fermi-orbital-descriptor permutations. The results of these analyses predict the percentage of open-shell character in O3, which agrees well with conventional wavefunction-based methods. While these techniques are expected to be required in cases near the Coulson–Fischer point, we find that they will be less necessary in diradical systems with well-separated electrons, such as (C21H13)2. Results based on energies from self-interaction-corrected generalized gradient, local density, and Hartree–Fock approximations and experimental results are in generally good agreement for O3. These results help form the basis for deriving extended Heisenberg-like Hamiltonians that are needed for descriptions of molecular magnets when there are competing low-energy electronic configurations. [ABSTRACT FROM AUTHOR]

We numerically study the strong-interaction limit of the exchange–correlation functional for neutral atoms and Bohr atoms as the number of electrons increases. Using a compact representation, we analyze the second-order gradient expansion, comparing it with the one for exchange (weak interaction limit). The two gradient expansions, at strong and weak interaction, turn out to be very similar in magnitude but with opposite signs. We find that the point-charge plus continuum model is surprisingly accurate for the gradient expansion coefficient at strong coupling, while generalized gradient approximations, such as Perdew–Burke–Ernzerhof (PBE) and PBEsol, severely underestimate it. We then use our results to analyze the Lieb–Oxford bound from the point of view of slowly varying densities, clarifying some aspects on the bound at a fixed number of electrons. [ABSTRACT FROM AUTHOR]

This document is an erratum for a journal article that corrects errors in the implementation of equations. It provides corrected values for eigenvectors and perturbative correction terms. The document also presents data on triplet exciton transfer couplings in anthracene dimers and singlet fission couplings for pentacene dimers. The corrected tables compare couplings for different compounds and calculation methods, and provide excitation energies and weights of basis states for pentacene dimers. This information can be useful for researchers studying singlet fission and its applications. The correction was provided by Soichiro Nishio and Yuki Kurashige. [Extracted from the article]

The nuclear and magnetic structures of CaxSr2−xWMnO6 (x = 0.5, 1.0, 1.5) have been investigated by neutron diffraction at 295, 30 or 40 K, and 4 or 5 K. The compounds crystallized in the monoclinic symmetry with a space group P21/n. The nuclear structure consists of ordered WO6 and Mn2+O6 octahedral frameworks, with lattice constant a decreasing more rapidly than b with increasing Ca content. No structural change was found around the magnetic transition temperature, although the Mn octahedron below the magnetic order temperature exhibited a slightly compressed Jahn–Teller distortion (0.1–0.3 Å) along the c axis. A standard magnetic model was used to solve the magnetic structure, with the Mn magnetic moments ferromagnetically coupled along the a axis and anti-ferromagnetically coupled along the b and c axes, resulting in a magnetic propagation vector of k = (0,1/2, 1/2) and a magnetic superlattice of 1a × 2b × 2c. In each crystallographic cell, the Mn1–Mn2 atoms are antiferromagnetically configurated, compensating the total moment to zero by symmetry. A layer-type magnetism along the (111) crystallographic plane was confirmed to couple antiferromagnetically between these planes and ferromagnetically within them. The magnetic structure refinement confirmed an average Mn moment of 4.5 μB. Also, it reveals that the collinear magnetic Mn configuration has three possible spin orientations, namely, (with their standard deviation) [μx = (3.3 ± 0.4) μB, μy = (2.5 ± 0.3) μB, μz = (−0.7 ± 0.7) μB], [μx = (3.0 ± 0.4) μB, μy = (0.5 ± 0.2) μB, μz = (−2.8 ± 0.2) μB, and [μx = (−1.8 ± 0.4) μB, μy = (2.9 ± 0.2) μB, μz = (−2.4 ± 0.3) μB. The first configuration is estimated to be the ground state, while the other magnetic configurations are an optimum local value derived from the refinements. Combined with the density functional theory calculations, these experimental results confirm a high-spin state Mn2+ (d5) electron configuration. [ABSTRACT FROM AUTHOR]

We report a study on the electronic structure and chemical bonding of the BiB molecule using high-resolution photoelectron imaging of cryogenically cooled BiB− anion. By eliminating all the vibrational hot bands, we can resolve the complicated detachment transitions due to the open-shell nature of BiB and the strong spin–orbit coupling. The electron affinity of BiB is measured to be 2.010(1) eV. The ground state of BiB− is determined to be 2Π(3/2) with a σ2π3 valence electron configuration, while the ground state of BiB is found to be 3Σ−(0+) with a σ2π2 electron configuration. Eight low-lying spin–orbit excited states [3Σ−(1), 1Δ(2), 1Σ+(0+), 3Π(2), 3Π(1), 1Π(1)], including two forbidden transitions, [3Π(0−) and 3Π(0+)], are observed for BiB as a result of electron detachment from the σ and π orbitals of BiB−. The angular distribution information from the photoelectron imaging is found to be critical to distinguish detachment transitions from the σ or π orbital for the spectral assignment. This study provides a wealth of information about the low-lying electronic states and spin–orbit coupling of BiB, demonstrating the importance of cryogenic cooling for obtaining well-resolved photoelectron spectra for size-selected clusters produced from a laser vaporization cluster source. [ABSTRACT FROM AUTHOR]

Accurate multireference electronic structure calculations are important for constructing potential energy surfaces. Still, even in the case of low-scaling methods, their routine use is limited by the steep growth of the computational and storage costs as the active space grows. This is primarily due to the occurrence of three- and higher-body density matrices or, equivalently, their cumulants. This work examines the effect of various cumulant truncation schemes on the accuracy of the driven similarity renormalization group second-order multireference perturbation theory. We test four different levels of three-body reduced density cumulant truncations that set different classes of cumulant elements to zero. Our test cases include the singlet–triplet gap of CH2, the potential energy curves of the X Σ g + 1 and A Σ u + 3 states of N2, and the singlet–triplet splittings of oligoacenes. Our results show that both relative and absolute errors introduced by these cumulant truncations can be as small as 0.5 kcal mol−1 or less. At the same time, the amount of memory required is reduced from O ( N A 6 ) to O ( N A 5 ) , where NA is the number of active orbitals. No additional regularization is needed to prevent the intruder state problem in the cumulant-truncated second-order driven similarity renormalization group multireference perturbation theory methods. [ABSTRACT FROM AUTHOR]

Recent measurements of the third harmonic scattering responses of molecules have given a new impetus for computing molecular second hyperpolarizabilities (γ) and for deducing structure–property relationships. This paper has employed a variety of wavefunction and density functional theory methods to evaluate the second hyperpolarizability of the p-nitroaniline prototypical push-pull π-conjugated molecule, addressing also numerical aspects, such as the selection of an integration grid and the impact of the order of differentiation vs the achievable accuracy by using the Romberg quadrature. The reliability of the different methods has been assessed by comparison to reference Coupled-Cluster Singles and Doubles with perturbative treatment of the Triples results. On the one hand, among wavefunction methods, the MP2 scheme offers the best accuracy/cost ratio for computing the static γ. On the other hand, using density functional theory, γ remains a challenging property to compute because all conventional, global hybrid or range-separated hybrid, exchange–correlation functionals underestimate static γ values by at least 15%. Even tuning the range-separating parameter to minimize the delocalization errors does not enable to improve the γ values. Nevertheless, the original double-hybrid B2-PLYP functional, which benefits from 27% of PT2 correlation and 53% Hartree–Fock exchange, provides accurate estimates of static γ values. Unfortunately, the best performing exchange–correlation functionals for γ are not necessarily reliable for the first hyperpolarizability, β, and vice versa. In fact, the β of p-nitroaniline (pNA) could be predicted, with a good accuracy, with several hybrid exchange–correlation functionals (including by tuning the range-separating parameter), but these systematically underestimate γ. As for γ, the MP2 wavefunction method remains the best compromise to evaluate the first hyperpolarizability of pNA at low computational cost. [ABSTRACT FROM AUTHOR]

It is known that some non-dynamic effects of electron correlation can be included in coupled cluster theory using a tailoring technique that separates the effects of non-dynamic and dynamic correlations. Recently, the simple pCCD (pair coupled cluster doubles) wavefunction was shown to provide good results for some non-dynamic correlation problems, such as bond-breaking, in a spin-adapted way with no active space selection. In this paper, we report a study of excited states using "tailored coupled cluster singles and doubles," to attempt to use pCCD as a kernel for more complete coupled-cluster singles and doubles (CCSD) results for excited states. Several excited states are explored from those primarily due to single excitations to those dominated by doubly excited states and from singlet–triplet splittings for some diradical states. For the first two situations, tailored pCCD-TCCSD offers no improvement over equation of motion-CCSD. However, when we explore the singlet–triplet gap of diradical molecules that are manifestly multi-reference, a pCCD kernel provides improved results, particularly with generalized valence bond orbitals. [ABSTRACT FROM AUTHOR]

[Display omitted] It is critical and challenging to develop highly active and low cost bifunctional electrocatalysts for the hydrogen/oxygen evolution reaction (HER/OER) in water electrolysis. Herein, we propose cerium-vanadium-based hollow nanopillar arrays supported on nickel foam (CeV-HNA/NF) as bifunctional HER/OER electrocatalysts, which are prepared by etching the V metal–organic framework with Ce salt and then pyrolyzing. Etching results in multidimensional optimizations of electrocatalysts, covering substantial oxygen vacancies, optimized electronic configurations, and an open-type structure of hollow nanopillar arrays, which contribute to accelerating the charge transfer rate, regulating the adsorption energy of H/O-containing reaction intermediates, and fully exposing the active sites. The reconstruction of the electrocatalyst is also accelerated by Ce doping, which results in highly active hydroxy vanadium oxide interfaces. Therefore, extremely low overpotentials of 170 and 240 mV under a current density of 100 mA cm−2 are achieved for the HER and OER under alkaline conditions, respectively, with long-term stability for 300 h. An electrolysis cell with CeV-HNA/NF as both the cathode and anode delivers a small voltage of 1.53 V to achieve water electrolysis under 10 mA cm−2, accompanied by superior durability for 150 h. This design provides an innovative way to develop advanced bifunctional electrocatalysts for overall water electrolysis. [ABSTRACT FROM AUTHOR]

A Setaria-like NiTe 2 /MoS 2 @C heterojunction is synthesized through one-step hydrothermal method followed by a carbonisation process. The NiTe 2 /MoS 2 heterojunctions exhibit low lattice misfits (δ =13%), strong electric fields, and uniform carbon shells, thus resulting in unique electronic structures and abundant active sites. [Display omitted] • Setaria-like NiTe 2 /MoS 2 @C heterojunctions are synthesized as anode for KIB. • MoS 2 nanosheets embedded in NiTe 2 nanorods to form stabilized heterojunctions. • The NiTe 2 /MoS 2 heterojunctions show low lattice misfits and strong electric fields. • The NiTe 2 /MoS 2 @C delivers the ultralong cycle stability and rate performance for KIB. Constructing unique heterostructures is a highly effective approach for enhancing the K+ storage capability of transition metal selenides. Such structures generate internal electric fields that significantly reduce the charge transfer activation energy. However, achieving a flawless interfacial region that maintains the optimal energy level gradient and degree of lattice matching remains a considerable challenge. In this study, we synthesised Setaria-like NiTe 2 /MoS 2 @C heterogeneous interfaces at which three-dimensional MoS 2 nanosheets are evenly embedded in NiTe 2 nanorods to form stabilised heterojunctions. The NiTe 2 /MoS 2 heterojunctions display distinctive electronic configurations and several active sites owing to their low lattice misfits (δ = 13 %), strong electric fields, and uniform carbon shells. A NiTe 2 /MoS 2 @C anode in a potassium-ion battery (KIB) exhibited an impressive reversible capacity of 125.8 mAh/g after 1000 cycles at a rate of 500 mA g−1 and a stable reversible capacity of 111.7 mAh/g even after 3000 cycles at 1000 mA g−1. Even the NiTe 2 /MoS 2 @C//perylene tetracarboxylic dianhydride full battery configuration maintained a significant reversible capacity of 92.4 mAh/g after 100 cycles at 200 mA g−1, highlighting its considerable potential for application in KIBs. Calculations further revealed that the well-designed NiTe 2 /MoS 2 heterojunction significantly promotes K+ ion diffusion. [ABSTRACT FROM AUTHOR]

Title hybrid iron(II)- and cobalt(III)-centered complexes were prepared in moderate yields using the template reactions of 3-acetylpyrazoloxime as a chelating ligand synthon with a Lewis-acidic zirconium or hafnium(IV) phthalocyaninate on the corresponding 3d-metal ion as a matrix. Formation of the cobalt(III)-centered complexes is observed due to the oxidation of Co2+ cations of the initial cobalt(II) salt. Thus obtained binuclear chloride H-bonded iron(II) and cobalt(III) compounds were characterized using elemental analysis, 1H and 13C {1H} NMR, MALDI-TOF mass, 57Fe Mössbauer (for iron compounds) and UV-vis spectra, and by single-crystal X-ray diffraction (XRD). Their redox properties were studied by cyclic (CV) and differential pulse voltammetry methods, and using spectroelectrochemical experiments. Their encapsulated 3d-metal ions with the electronic d6 configuration are located almost in the center of MN6-coordination polyhedra, the geometry of which is more closer to a trigonal antiprism (TAP, the distortion angle ϕ = 60°) than to a trigonal prism (TP, ϕ = 0°) with ϕ ∼ 40°. FeII–N distances fall in the range 1.913(6)–1.965(7) Å, while the CoIII–N bond lengths are from 1.890(8) to 1.935(8) Å. The geometry of MIVO3N4-coordination polyhedra of their capping metal(IV) ions is intermediate between a capped TAP and a capped TP. In the molecules of ZrIVMIIIMIIMIIZrIV-pentanuclear intracomplexes, (HS)FeIII–N and (LS)CoIII–N distances in their two semiclathrochelate fragments fall in the ranges 1.915(10)–1.980(12) Å and 1.886(13)–1.930(13) Å, respectively, and the geometry of MN6-coordination polyhedra is closer to a TAP (values of ϕ are higher than 30°). The geometry of MN6-polyhedra of the HS cross-linking metal(II) ions between them is close to a TAP (values of ϕ are higher than 50°). All the obtained binuclear hybrid complexes exhibit very similar electrochemical patterns. Their CVs contain quasi-reversible or irreversible three reduction and three oxidation waves. The potentials of electrochemical reductions, assigned to the Pc-localized redox processes, are close to each other. The first of them is a quasi-reversible process attributed to the Pc-based one-electron reduction, while the first oxidation wave was assigned to the metal-centered M2+/3+ redox couples. The spectroelectrochemical data confirmed an assignment of the aforementioned electrochemical processes. [ABSTRACT FROM AUTHOR]

Ru‐based pyrochlores (e.g. Y2Ru2O7−δ) are promised to replace IrO2 in polymer electrolyte membrane (PEM) electrolyzers. It is significant to reveal the cliff attenuation on the oxygen evolution reaction (OER) performance of these pyrochlores. In this work, we monitor the structure changes and electrochemical behavior of Y2Ru2O7−δ over the OER process, and it is found that the reason of decisive OER inactivation is derived from an insulator transition occurred within Y2Ru2O7−δ due to its inner "perfecting" lattice induced by continuous atom rearrangement. Therefore, a stabilization strategy of the Ir‐substituted Y2Ru2O7−δ is proposed to alleviate this undesirable behavior. The double‐exchange interaction between Ru and Ir in [RuO6] and [IrO6] octahedra leads the charge redistribution with simultaneous spin configuration adjustment. The electronic state in newly formed octahedrons centered with Ru 4d3 (with the state of eg′↑↑a1g↑eg0) and Ir 5d6 (eg′↑↓↑↓a1g↑↓eg0) relieves the uneven electron distributions in [RuO6] orbital. The attenuated Jahn–Teller effect alleviates atom rearrangement, represented as the mitigation of insulator transition, surface reconstruction, and metal dissolution. As results, the Ir‐substituted Y2Ru2O7−δ presents the greatly improved OER stability and PEM durability. This study unveils the OER degradation mechanism and stabilization strategy for material design of Ru‐based OER catalysts for electrochemical applications. [ABSTRACT FROM AUTHOR]

We present the angular distribution of the ejected electron for single ionization of He by fast proton impact. A four-body formalism of the three-Coulomb wave is applied to calculate the triple differential cross sections at several impact energies in the scattering, perpendicular and azimuthal planes. Moreover, the three-body formalism of three-Coulomb, two-Coulomb and first Born approximation models has also been used to study the many-body effect on electron emission and the validity of the models. In the three-Coulomb wave model, the final state wave function incorporates distortion due to the three-body mutual Coulombic interaction. In this formalism, we use an uncorrelated and correlated Born initial state, which consists of a plane wave for the incoming projectile times a two-electron bound state wavefunction of the helium atom representing the 1s2(1S) state. But, in the case of the three-body formalism, the initial state wavefunction consists of a long-range Coulomb distortion for the incoming projectile and one active electron of the He atom described by the Roothaan–Hartree–Fock wavefunction. The structure with a single or two peaks with unequal intensity is observed in the angular distributions of the triple differential cross sections for the different kinematic conditions. In addition, the influence of static electron correlations is investigated using different bound state wavefunctions for the ground state of the He target. In the four-body formalism, the present computations are very fast by reducing a nine-dimensional integral to a two-dimensional real integral. Despite the simplicity and speed of the proposed quadrature, the comparison shows that the obtained results are in reasonable agreement with the experiment and are compatible with those of other theories. [ABSTRACT FROM AUTHOR]

This study investigates organotin (IV) complexes derived from the recently synthesized quinazoline Schiff base ligand (L). The research involves synthesizing and characterizing these complexes, including elemental analysis, UV–visible, FT‐IR, mass spectra, and conductometric measurements. Advanced studies such as density functional theory (DFT) are employed to gain insights into the stable electronic configuration. Specifically, the study explores the proposed geometry, revealing a distorted octahedral structure for the complexes. The findings contribute as critical molecular characteristics of these newly synthesized complexes, paving the way for potential applications in diverse fields, including medicinal chemistry. Through an investigation into the antimicrobial properties, the efficacy of the synthesized compounds was assessed against a diverse range of bacterial and fungal strains. Remarkably, the complexes demonstrated significant antimicrobial activities, showing potential applications in combating various microbial infections. In an extended exploration of their medical utility, the compounds were examined for their antibiotic properties against Helicobacter pylori. The Schiff base and its metal complexes emerged as promising antibiotics with notable efficacy against H. pylori, suggesting their potential in addressing infections associated with this bacterium. Furthermore, the antitumor potential of the synthesized complexes was investigated, focusing on their impact on MCF‐7 (Breast carcinoma) cells. The organotin (IV) Schiff base complexes in this research showed remarkable efficacy, evidenced by their notably low IC50 values (9, 10, 11 μg/mL) in comparison with cisplatin. In addition to their potent antitumor effects, these complexes exhibited reduced cytotoxicity toward normal cells (VERO cells) compared with cisplatin. The investigation extends to molecular docking, where this approach aims to elucidate their interactions with specific protein structures, including (2JFZ, 1SC7, and 6W41). The primary objective is to clarify the potential properties of these compounds, focusing on their antibiotic efficacy, anti‐H. pylori activity, antitumor potential, and anti‐COVID‐19 properties. [ABSTRACT FROM AUTHOR]

Electronic configuration regulation is usually a feasible strategy to boost the electrocatalytic performance for transition metal oxides. Herein, a simple high-temperature annealing method is employed to optimize the electrocatalytic activity towards hydrogen evolution reaction (HER) for spinel oxide Co 3 O 4. The experimental results indicate the simple thermal treatment partially drives the structure reversal in spinel Co 3 O 4 , and it induces the redistribution of cobalt ions at tetrahedral and octahedral sites. Thereby, the electronic configuration regulation occurs, and the e g occupation of cobalt ions at octahedral sites increases up to 1, optimizing the HER reaction kinetics. The sample treated at 900 °C exhibits the highest activity, with overpotential of 335 mV at current density of 10 mA cm−2, and Tafel slope value of 99.3 mV dec−1. This work offers a new way of tuning the electronic configuration in spinel oxides to boost HER electrocatalytic activity. • A simple high-temperature annealing method was adopted to partially drive the structure reversal in Co 3 O 4. • Partial structure reversal can induce redistribution of cobalt ions, and effectively modulate electronic configuration. • Complex spinel exhibited better HER activity than that of normal spinel. [ABSTRACT FROM AUTHOR]

[Display omitted] Hydrogen peroxide (H 2 O 2) emerges as a viable oxidant for fuel cells, necessitating the development of an efficient and cost-effective electrocatalyst for the hydrogen peroxide reduction reaction (HPRR). In this study, we synthesized a self-supporting, highly active HPRR electrocatalyst comprising two morphologically distinct components: CeO 2 -NiCo 2 O 4 nanowires and CeO 2 -NiCo 2 O 4 metal organic framework derivatives, via a two-step hydrothermal process followed by air calcination. X-ray diffraction and transmission electron microscopy analysis confirmed the presence of CeO 2 and NiCo 2 O 4 , revealing the amalgamated interface between them. CeO 2 exhibits multifunctionality in regulating the surface electronic configuration of NiCo 2 O 4 , fostering synergistic connections, and introducing oxygen deficiencies to enhance the catalytic efficacy in HPRR. Electrochemical measurements demonstrate a reduction current density of 789.9 mA·cm−2 at −0.8 V vs. Ag/AgCl. The assembly of direct borohydride-hydrogen peroxide fuel cell (DBHPFC) exhibits a peak power density of 45.2 mW·cm−2, demonstrating durable stability over a continuous operation period of 120 h. This investigation providing evidence that the fabrication of heterostructured catalysts based on CeO 2 for HPRR is a viable approach for the development of high-efficiency electrocatalysts in fuel cell technology. [ABSTRACT FROM AUTHOR]

Designing and exploiting visible‐light‐responsive materials that converts solar into chemical energy is promising in achieving green energy sustainability, but addressing low electron–hole separation efficiency and sluggish surface kinetic process remains formidable challenges. Herein, a novel CoP@Ni‐CdS Schottky junction composed of Ni‐doped CdS nanorods and quasi‐metallic CoP nanoparticles is constructed via a simple hydrothermal–calcination method. Experiments and theoretical calculations demonstrate that magnetic Ni‐doping not only induces a spin‐polarized electric field and enhances the built‐in interfacial electric field strength, but also rises the Schottky barrier height at the heterointerface, which synergistically accelerates the separation efficiency of photoinduced charges and modulates the electronic configuration of the active site to optimize the adsorption–desorption behaviors for H2O molecules and H* intermediates. Therefore, the designed CoP@Ni‐CdS catalyst exhibits an exceptional photocatalytic performance with H2 evolution rate of 42.14 mmol g−1 h−1 with the apparent quantum efficiencies of 16.8% at 420 nm, which is 14.14 and 2.21 times higher than that of pristine CdS and Ni‐CdS, respectively. This work provides in‐depth insights into fabricating dual electric fields, tuning the Schottky barrier and modulating the electronic configuration of active sites in Schottky heterojunction for ameliorative photocatalytic activity. [ABSTRACT FROM AUTHOR]

Understanding the microenvironment structure‐activity relationship of singlet‐atom catalysts (SACs) is imperative for the development of high‐performance photocatalytic devices. However, the challenge remains to finely regulate the coordination microenvironment of SACs. Herein, single‐atom Nx─Cu─O4‐x (x = 1–4) photocatalysts with different coordination environments are successfully prepared based on pre‐design reticular supramolecular covalent organic frameworks (COFs) for direct photocatalytic 1O2 production from O2. The results show that the high activity of Cu SACs is closely related to the N,O‐coordination microenvironment, which is primarily ascribed to the different electrophilicity of the N, O atom. The electron configuration of N3‐Cu‐O1 endows photocatalyst enhanced charge transfer capability and the nearest D‐band center to the Fermi level. The "end‐on" type adsorption configuration of O2 at the N3─Cu─O1 active site can promote the breaking of Cu─O bonds rather than O─O bonds. As a result, the N3‐Cu‐O1@COF photocatalyst exhibits the most optimal formation and desorption energies for intermediates •OOH, which provides an advantageous reaction pathway with fewer steps and a lower barrier for 1O2 production. This work highlights the structure‐activity relationship of SACs for long‐term applications. [ABSTRACT FROM AUTHOR]

Constructing atomic‐scale dispersed noble metal electrocatalysts holds enormous potential toward alkaline hydrogen oxidation reactions (HOR) owing to the high intrinsic activity and atom utilization. Here, this work shows that Ir clusters anchored on different types of molybdenum carbides (Ir/α‐MoC1‐x, Ir/β‐Mo2C) with tunable electronic interactions display distinct performance in alkaline HOR. Notably, the mass activity of Ir/α‐MoC1‐x with stronger electronic interaction is roughly twice that of Ir/β‐Mo2C. Moreover, the Ir/α‐MoC1‐x has reached an impressive mass‐normalized exchange current density (j0, mass) of 320 mA mg−1metal, making the HOR properties are comparable to those recently reported excellent alkaline HOR Ir‐based electrocatalysts. Both experimental and theoretical calculations have confirmed that the strong metal‐substrate interaction of Ir/α‐MoC1‐x via interfacial Ir‐Mo bonding, leading to a significantly modulated electronic structure and optimized binding energy of H* and OH*, thereby promoting the reaction kinetics of alkaline HOR. This work highlights strong metal‐support interactions can be an effective scheme for regulating the local electronic configuration and adsorption behavior of the catalyst along with an improved intrinsic catalytic activity. [ABSTRACT FROM AUTHOR]

Anion defect engineering is proven to be an efficient approach to reconstruct the electronic configuration of carbon‐based magnetoelectric materials for targeted modulation of electromagnetic (EM) performance. However, traditional mono‐anionic doping suffers from low defect concentration and lacks diverse polarization mechanisms. In this work, multi‐anions (N/S/F) stepwise‐doped carbon/Fe3C magnetoelectric composites are elaborately constructed, wherein the predesigned N defects serve as activated sites for anomalously adopting S anions (Step I) and subsequent F anions (Step II) in non‐marginal areas of the carbon layer. It is found that S prefers to replace pyrrolic N defects while F tends to form dangling bonds with the C site adjacent to the pyridinic N. Intriguingly, besides the inherent polarized resonance of N defect at ≈15 GHz, customized S and F defects induce new polarization resonances at ≈10 GHz and ≈15+ GHz, respectively. Under a typical multi‐polarization effect with the synergetic magnetic response, the carbon/Fe3C composites with N/S/F defects harvest the broadest bandwidth of 8.28 GHz (9.72–18 GHz) at 2.55 mm, covering a wide frequency range almost from X to Ku bands. This work demonstrates the positive impact of localized multi‐defects customization and multi‐polarization effect on expanding microwave absorption bandwidth, providing valuable insights for the advanced design of ultra‐broadband absorbers. [ABSTRACT FROM AUTHOR]