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• GFs were integrated with ANF through sol-hydrogel-paper process. • GF/ANF paper possess thermally conductive yet electrically insulating property. • Vibrational properties of GF and ANF were studied using ab initio calculation. • Superb mechanical properties with a remarkable toughness and strength were achieved. • Excellent thermal stability and nonflammability were obtained. Heat dissipation is a critical requirement for the innovation of fifth-generation (5G) electronics, and in turn, for the unceasing development of highly efficient heat-dissipating materials (HDMs). In 5G electronics, high thermoconductive yet electrically insulating HDMs with lightweight, excellent flexibility, and outstanding thermal properties have a high demand. In this study, we developed a fabulous HDM with superior mechanical properties, high thermal conductivity, and electrical insulation. The underlying principle involves taking advantage of graphene fluoride (GF), which is an emerging two-dimensional (2D) material that is highly thermally conductive, along with an electrically insulating material. By integrating a 2D GF sheet in a three-dimensional (3D) interconnected aramid nanofiber (ANF) network, a paper was successfully fabricated via a scalable process of sol-hydrogel-paper transformation. The resultant GF/ANF paper showed excellent mechanical properties with a remarkable strength of 188 MPa and toughness of 107 MJ m−3. These exceptional results are attributed to the formation of a nacre-inspired structure with strong hydrogen bonding between the GF sheet and ANF matrix and the extensive elongation of the entangled 3D ANF. Notably, the GF/ANF nacre-inspired paper with 40 wt% GF content achieved a thermal conductivity and volume resistivity as high as 48.2 W m−1 K−1 and 2.7 × 1015 Ω m, respectively. Moreover, the vibrational properties of GF and ANF were extensively investigated via ab initio calculations. The paper exhibited excellent thermal stability, non-flammability, and high efficiency in heat dissipation in an organic light-emitting diode system. It demonstrated the best overall performance among the representative HDMs analyzed, representing a critical breakthrough in the fabrication of HDMs toward practical applications in wearable electronic devices. [ABSTRACT FROM AUTHOR]

This paper presents results of a comprehensive study from first principles into the properties of Ni, Pd, Rh, and Ir crystals under pressure. We calculated elastic constants, phonon spectra, isotherms, Hugoniots, sound velocities, relative structural stability, and phase diagrams. It is shown that in nickel and palladium under high pressures (>0.14 TPa) and temperatures (>4 kK), the body-centered cubic structure is thermodynamically most stable than of the face-centered cubic one. Calculated results suggest that nickel under Earth-core conditions (P ∼ 0.3 TPa, T ∼ 6 kK) have a bcc structure. No structural changes were found to occur in Rh and Ir under pressures to 1 TPa at least. This paper also provides estimations for the pressure and temperature at which the metals of interest begin to melt under shock compression. [ABSTRACT FROM AUTHOR]

The editorial on oxidation in complex atmospheres discusses the impact of multiple oxidants on metal parts in various industrial processes, emphasizing the importance of considering molecules like H2, H2O, and NH3 in corrosion mechanisms. The collection of papers presented at the 11th International Conference on High-Temperature Corrosion and Protection of Materials explores how oxidation interacts with carburizing, nitriding, and sulfidizing reactions, as well as the effects of water vapor on different alloys. The research highlights the role of thermodynamic and ab initio calculations in addressing complex corrosion issues, providing valuable insights for the development and selection of alloys in challenging environments. [Extracted from the article]

This research paper presents a new fundamental approach for evaluating accurate ab initio quartic, sextic, and octic centrifugal distortion parameters of A-reduced rotational effective Hamiltonians of asymmetric top molecules. In this framework, the original Watson Hamiltonian, expanded up to sextic terms of kinetic and potential energies, is subjected to a series of vibrational and rotational operator unitary transformations, leading to reduced Watson effective Hamiltonians for the equilibrium configuration, ground state, and weakly perturbed vibrationally excited states. The proposed scheme is based on a numerical-analytic implementation of the sixth-order Van Vleck operator perturbation theory with the systematic normal ordering of vibrational rising and lowering operators (a†, a) and cylindrical angular momentum operators (Jz, J+, J−). The efficiency of the developed theoretical model is demonstrated by the juxtaposition of predicted centrifugal distortion parameters for several three to eight atomic molecules, including H2S, CH2O, C2H4, CH2D2, CH2F2, CH2Cl2, and B2H6, using the coupled-cluster single double triple/quadruple-ζ level of quantum chemistry. In comparison with the values derived using the customary analytic expressions, the calculated quartic and sextic parameters may improve by an order of magnitude in the fourth and sixth orders, respectively, reaching an accuracy of about 1%. Predicted octic constants can serve as an excellent starting point for fitting to experimental spectra. [ABSTRACT FROM AUTHOR]

TurboGenius is an open-source Python package designed to fully control ab initio quantum Monte Carlo (QMC) jobs using a Python script, which allows one to perform high-throughput calculations combined with TurboRVB [Nakano et al. J. Phys. Chem. 152, 204121 (2020)]. This paper provides an overview of the TurboGenius package and showcases several results obtained in a high-throughput mode. For the purpose of performing high-throughput calculations with TurboGenius, we implemented another open-source Python package, TurboWorkflows, that enables one to construct simple workflows using TurboGenius. We demonstrate its effectiveness by performing (1) validations of density functional theory (DFT) and QMC drivers as implemented in the TurboRVB package and (2) benchmarks of Diffusion Monte Carlo (DMC) calculations for several datasets. For (1), we checked inter-package consistencies between TurboRVB and other established quantum chemistry packages. By doing so, we confirmed that DFT energies obtained by PySCF are consistent with those obtained by TurboRVB within the local density approximation (LDA) and that Hartree–Fock (HF) energies obtained by PySCF and Quantum Package are consistent with variational Monte Carlo energies obtained by TurboRVB with the HF wavefunctions. These validation tests constitute a further reliability check of the TurboRVB package. For (2), we benchmarked the atomization energies of the Gaussian-2 set, the binding energies of the S22, A24, and SCAI sets, and the equilibrium lattice parameters of 12 cubic crystals using DMC calculations. We found that, for all compounds analyzed here, the DMC calculations with the LDA nodal surface give satisfactory results, i.e., consistent either with high-level computational or with experimental reference values. [ABSTRACT FROM AUTHOR]

Lanthanides play the most important roles in the opacities for kilonova, ultraviolet–optical–infrared emission from neutron star mergers. Although several efforts have been made to construct atomic data, the accuracy of the opacity is not fully assessed and understood. In this paper, we perform atomic calculations for singly ionized lanthanides with improved strategies, aiming at understanding the physics of the lanthanide opacities in kilonova ejecta and necessary accuracy in atomic data. Our results show systematically lower energy level distributions as compared with our previous study (Paper I). As a result, the opacities evaluated with our new results are higher by a factor of up to |$3 \!-\! 10$|⁠ , depending on the element and wavelength range. For a lanthanide-rich element mixture, our results give a higher opacity than that in Paper I by a factor of about 1.5. We also present opacities by using the results of ab initio atomic calculations by using grasp2k code. In general, our new opacities show good agreements with those with ab initio calculations. We identify that structure of the lanthanide opacities is controlled by transition arrays among several configurations, for which derivation of accurate energy level distribution is important to obtain reliable opacities. [ABSTRACT FROM AUTHOR]

This paper presents a theoretical investigation utilizing the full-potential linearized augmented planewave method (FP-LAPW) within density functional theory (DFT) framework, implemented in the Wien2k program. Analysis reveals that Sr2DySbO6 (t = 0.991) and Sr2LaSbO6 (t = 1.01) exhibit theoretical tolerance factors suggesting their crystallization in a face-centered cubic form (FCC) with space group (Fm3m; No. 225). Notably, Sr2DySbO6 demonstrates a slightly higher stability (χ_ value of 2.1207) compared to Sr2LaSbO6 (χ_ value of 1.9902). Both compounds also show negative formation energies, suggesting that they are feasible for experimental synthesis and structurally stable. Stability is further confirmed by structural optimization by atomic relaxation and total energy reduction against unit cell volume. Both compounds exhibit ductility, anisotropy, ionic bonding nature, elastic stability, resistance to plastic deformation, and central force crystal properties. Sr2DySbO6 electronic characteristics reveals that it is metallic, whereas Sr2LaSbO6 is insulating. Energy-wise, optical properties are assessed between 0 and 15 eV. Both the compounds have demonstrated noteworthy UV responses are making use of the unique characteristics and high energy of UV light for a range of creative uses. Overall, these findings advocate for experimental exploration of these compounds, hinting at potential applications. [ABSTRACT FROM AUTHOR]

The electron transitions in atoms caused by charged particle impact are benchmarks for the study of electron dynamics. In the present paper we focus on the excitation of helium by proton and antiproton impact. We perform both ab initio and perturbational calculations, revealing the importance of electron correlations and higher-order effects. The influence of the projectile charge sign on the excitation cross section is also studied. [ABSTRACT FROM AUTHOR]

The analysis and modeling of high-resolution spectra of nonrigid molecules require a specific Hamiltonian and group-theoretical formulation that differs significantly from that of more familiar rigid systems. Within the framework of Hougen–Bunker–Johns (HBJ) theory, this paper is devoted to the construction of a nonrigid Hamiltonian based on a suitable combination of numerical calculations for the nonrigid part in conjunction with the irreducible tensor operator method for the rigid part. For the first time, a variational calculation from ab initio potential energy surfaces is performed using the HBJ kinetic energy operator built from vibrational, large-amplitude motion, and rotational tensor operators expressed in terms of curvilinear and normal coordinates. Group theory for nonrigid molecules plays a central role in the characterization of the overall tunneling splittings and is discussed in the present approach. The construction of the dipole moment operator is also examined. Validation tests consisting of a careful convergence study of the energy levels as well as a comparison of results obtained from independent computer codes are given for the nonrigid molecules CH2, CH3, NH3, and H2O2. This work paves the way for the modeling of high-resolution spectra of larger nonrigid systems. [ABSTRACT FROM AUTHOR]

Simulations of exciton and charge hopping in amorphous organic materials involve numerous physical parameters. Each of these parameters must be computed from costly ab initio calculations before the simulation can commence, resulting in a significant computational overhead for studying exciton diffusion, especially in large and complex material datasets. While the idea of using machine learning to quickly predict these parameters has been explored previously, typical machine learning models require long training times, which ultimately contribute to simulation overheads. In this paper, we present a new machine learning architecture for building predictive models for intermolecular exciton coupling parameters. Our architecture is designed in such a way that the total training time is reduced compared to ordinary Gaussian process regression or kernel ridge regression models. Based on this architecture, we build a predictive model and use it to estimate the coupling parameters which enter into an exciton hopping simulation in amorphous pentacene. We show that this hopping simulation is able to achieve excellent predictions for exciton diffusion tensor elements and other properties as compared to a simulation using coupling parameters computed entirely from density functional theory. This result, along with the short training times afforded by our architecture, shows how machine learning can be used to reduce the high computational overheads associated with exciton and charge diffusion simulations in amorphous organic materials. [ABSTRACT FROM AUTHOR]

The analysis in the present paper is based on the most known concept introduced by the brilliant physicist Alexander Andreev: Andreev bound states in a normal metal sandwiched between two superconductors. The paper presents results of direct calculations of ab initio expressions for the currents in a long ballistic SNS junction. The expressions are expanded in 1/L (L is the thickness of the normal layer). The main contribution ∝ 1 / L to the current agrees with the results obtained in the past, but the analysis suggests a new physical picture of the charge transport through the junction free from the problem with the charge conservation law. The saw-tooth current-phase relation at T = 0 directly follows from the Galilean invariance of the Bogolyubov–de Gennes equations proved in the paper. The proof is valid for any variation of the energy gap in space if the Andreev reflection is the only scattering process. The respective roles of the contributions of bound and continuum states to the current are clarified. They depend on the junction dimensionality. [ABSTRACT FROM AUTHOR]

This paper first uses ab initio calculations for a systematic study of an influence of Cr, Mn, C, and P alloying elements on the grain boundary segregation of phosphorus in ferromagnetic α-Fe and its dependence on the nature of grain boundaries. Segregation energies of each element and site are fully calculated for two special grain boundaries of the types Σ3(111) and Σ5(310). We study the effect of grain boundary type on the segregation process of alloying elements. The estimate of effective segregation energy for each model of grain boundaries from the obtained segregation energies and analysis of the alloying element distribution at various boundary points are carried out. The paper shows that the Voronoi volume of a Fe site at the segregation point determines the segregation energy of the elements under study. The segregation energies of various pairs of impurities on the boundary are calculated. The effect of substitutional impurities on the change in the segregation energy of phosphorous atoms at the interstitial and substitutional sites and the effect of the phosphorous atom on the change in the impurity segregation energy at various boundary points are studied. The results obtained in this study correspond closely to the available experimental data and provide important base data for the design of high strength steel materials, and are useful for understanding the effect of alloying elements on bcc Fe. [ABSTRACT FROM AUTHOR]

FeRh-based alloys have attracted significant attention due to their magnetic phase transition and significant magnetocaloric effects. These properties position them as promising candidates for fundamental research and practical applications, including magnetic cooling and targeted drug delivery. The study of FeRh alloys, particularly those where Rhodium or Iron atoms are substituted with other transition metals, is crucial as certain substitutions preserve the alloy's magnetocaloric properties. However, even within a specific structural type and without considering competing phases, determining which atom (Fe or Rh) is replaced upon introducing a third element remains unclear. This paper addresses this ambiguity through ab initio calculations. We propose an approach to predict whether a dopant will replace Fe or Rh, offering insights into the electronic and structural factors influencing the substitution. Additionally, we present a dataset of ab initio calculations on doped FeRh alloys, which will support future data-driven modeling efforts. Our findings not only advance the understanding of FeRh-based alloys but also contribute to the design of novel materials for experimental and industrial applications. [ABSTRACT FROM AUTHOR]

Hexagonal boron nitride is rapidly gaining interest as a platform for photonic quantum technologies, due to its two-dimensional nature and its ability to host defects deep within its large band gap that may act as room-temperature single-photon emitters. In this review paper we provide an overview of (1) the structure, properties, growth and transfer of hexagonal boron nitride; (2) the creationof colour centres in hexagonal boron nitride and assignment of defects by comparison with ab initio calculations for applications in photonic quantum technologies; and (3) heterostructure devices for the electrical tuning and charge control of colour centres that form the basis for photonic quantum technology devices. The aim of this review is to provide readers a summary of progress in both defect engineering and device fabrication in hexagonal boron nitride based photonic quantum technologies. [ABSTRACT FROM AUTHOR]

Quantum Dot Cellular Automata (QCA) is an emerging trend in the field of nanoelectronics, and computing can be regarded as an alternative to the traditional complementary metal–oxide–semiconductor technology. The paper is devoted to the study of the key functional properties of the cells for molecular QCA based on mixed valence molecules. The theoretical results for the heat dissipation under the conditions of the fast nonadiabatic switching event and cell–cell response function are obtained in the framework of the quantum-mechanical vibronic approach. These results are parameterized using the previous reliable ab initio calculations performed for oxidized norbornadiene and its polycyclic derivatives with variable lengths of the bridge. The comparative analysis of the dimeric and bidimeric molecular cells composed of these compounds is given. It is underlined that the conditions of a strong non-linear response and a low heat release are contradictory. However, despite this problem, a parametric regime is proposed, which provides a low heat release in combination with a strong nonlinear response of the working cell to the electric field induced by the polarized driver cell. [ABSTRACT FROM AUTHOR]

Dilute magnetic semiconductors (DMSs) with both charge and spin degrees of freedom have emerged as promising candidates in the spintronic industry. However, the Curie temperature below room temperature and uncertainty about the origin of ferromagnetism hinder the application of DMSs. To address these issues, we explored a better SnO2-based co-doped method (Fe, V + VSn) using ab initio calculations. The calculation results show that the Sn13FeVO32 (Fe, V + VSn) has a high Curie temperature (716 K), good ferromagnetic properties, stronger covalency of bonds, and better optical transparency in the visible light range. In addition, the holes or electrons generated by the complexes in the (Fe, V + VO/VSn) co-doped system cause a spin-polarized double exchange effect in the Fe-3d, V-3d, and O-2p orbitals, which leads to magnetism of the co-doped systems. The static dielectric constant ɛ1(0) of the system increases after doping. Among them, Sn14FeVO31 (Fe, V + VO) has the largest ɛ1(0), indicating that Sn14FeVO31 has the strongest polarization ability and better photocatalytic properties. In Sn14FeVO31, the imaginary part of the dielectric function and the absorption spectrum all have new peaks in the low-energy region, which are caused by the jump of electrons from the guide band of the spin-polarized impurity energy level. This paper proposes a new method for preparing dilute magnetic semiconductors in spin electronic devices with high room temperature ferromagnetic properties and excellent optical properties through the (Fe, V + VO/VSn) co-doped SnO2. [ABSTRACT FROM AUTHOR]

In this paper, we will investigate the structural, electronic, mechanical, magnetic and optical properties of Heusler Mn2NiAl (MNA) compound using the Perdew–Burke–Ernzerhof generalized gradient approximation (PBE-GGA) of the full potential linearized augmented plane-wave method for exchange and use correlations, modified Becke–Johnson and GGA+U Hubbard parameter. The calculated band structure (BS) and density of states (DOS) of MNA showed a metallic (GGA), nearly half-metallic (mBJ) and half metallic (GGA+U) behavior. Moreover, the magnetic computed magnetic moments by GGA+U are higher compared to GGA and mBJ results. Bulk modulus, shear modulus, Voigt and Reuss polycrystalline elastic modulus, Debye temperature, sound velocities, the melting temperatures, B / G ratio, Young's modulus and Poisson's ratio were obtained. The elastic anisotropy of MNA alloy was analyzed using 2D and 3D figures of directional dependence of Poisson's ratio, shear modulus, linear compressibility and Young's modulus. Studies have shown that the Heusler material MNA has magnetic and anisotropic properties and is mechanically stable. [ABSTRACT FROM AUTHOR]

Two-dimensional (2D) materials promise advances in electronic devices beyond Moore's scaling law through extended functionality, such as non-monotonic dependence of device parameters on input parameters. However, the robustness and performance of effects like negative differential resistance (NDR) and anti-ambipolar behavior have been limited in scale and robustness by relying on atomic defects and complex heterojunctions. In this paper, we introduce a novel device concept that utilizes the quantum capacitance of junctions between 2D materials and molecular layers. We realized a variable capacitance 2D molecular junction (vc2Dmj) diode through the scalable integration of graphene and single layers of stearic acid. The vc2Dmj exhibits NDR with a substantial peak-to-valley ratio even at room temperature and an active negative resistance region. The origin of this unique behavior was identified through thermoelectric measurements and ab initio calculations to be a hybridization effect between graphene and the molecular layer. The enhancement of device parameters through morphology optimization highlights the potential of our approach toward new functionalities that advance the landscape of future electronics. [ABSTRACT FROM AUTHOR]

This paper reports for the first time on a new layered magnetic heterometallic erbium telluride EuErCuTe3. Single crystals of the compound were obtained from the elements at 1120 K using CsI as a flux. The crystal structure of EuErCuTe3 was solved in the space group Cmcm (a = 4.3086(3) Å, b = 14.3093(9) Å, and c = 11.1957(7) Å) with the KZrCuS3 structure type. In the orthorhombic structure of erbium telluride, distorted octahedra ([ErTe6]9−) form two-dimensional layers ( E r (T e 1) 2 / 2 e (T e 2) 4 / 2 k − ) ∞ 2 , while distorted tetrahedra ([CuTe4]7−) form one-dimensionally connected substructures ( C u (T e 1) 2 / 2 e (T e 2) 2 / 1 t 5 − ∞ 1 ) along the [100] direction. The distorted octahedra and tetrahedra form parallel two-dimensional layers ( C u E r T e 3 2 − ∞ 2) between which Eu2+ ions are located in a trigonal-prismatic coordination environment ( E u T e 6 10 −) . The trigonal prisms are connected by faces, forming chains ( E u (T e 1) 2 / 2 (T e 2) 4 / 2 2 − ∞ 1 ) along the [100] direction. Regularities in the variations in structural parameters were established in the series of erbium chalcogenides (EuErCuCh3 with Ch = S, Se, and Te) and tellurides (EuLnCuTe3 with Ln = Gd, Er, and Lu). Ab-initio calculations of the crystal structure, phonon spectrum, and elastic properties of the compound EuErCuTe3 were performed. The types and wavenumbers of fundamental modes were determined, and the involvement of ions in the IR and Raman modes was assessed. The experimental Raman spectra were interpreted. The telluride EuErCuTe3 at temperatures below 4.2 K was ferrimagnetic, as were the sulfide and selenide derivatives (EuErCuCh3 with Ch = S and Se). Its experimental magnetic characteristics were close to the calculated ones. The decrease in the magnetic phase transition temperature in the series of the erbium chalcogenides was discovered. [ABSTRACT FROM AUTHOR]

In this paper, a detailed mechanism is discussed for two processes: deNOx and deN2O. An FAU catalyst was used for the reaction with Cu-Fe bimetallic adsorbates represented by a dimer with bridged oxygen. Partial hydration of the metal centres in the dimer was considered. Ab initio calculations based on the density functional theory were used. The electron parameters of the structures obtained were also analysed. Visualisation of the orbitals of selected structures and their interpretations are presented. The presented research allowed a closer look at the mechanisms of processes that are very common in the automotive and chemical industries. Based on theoretical modelling, it was possible to propose the most efficient catalyst that could find potential application in industry–this is the FAU catalyst with a Cu-O-Fe bimetallic dimer with a hydrated copper centre. The essential result of our research is the improvement in the energetics of the reaction mechanism by the presence of an OH group, which will influence the way NO and NH3 molecules react with each other in the deNOx process depending on the industrial conditions of the process. Our theoretical results suggest also how to proceed with the dosage of NO and N2O during the industrial process to increase the desired reaction effect. [ABSTRACT FROM AUTHOR]

In this paper, we report a study of the low-lying states of deformed 21Ne within the framework of the quantum-number projected generator coordinate method (PGCM), starting from a chiral two-nucleon-plus-three-nucleon ( N N + 3 N ) interaction. The wave functions of states are constructed as a linear combination of a set of axially deformed Hartree–Fock–Bogliubov (HFB) wave functions with different quadrupole deformations. These HFB wave functions are projected onto different angular momenta and the correct neutron and proton numbers for 21Ne. The results of the calculations based on the effective Hamiltonians derived by normal-ordering the 3 N interaction with respect to three different reference states, including the quantum-number projected HFB wave functions for 20Ne, 22Ne, and an ensemble of them with equal weights, are compared. This study serves as a key step towards ab initio calculations of odd-mass deformed nuclei with the in-medium GCM. [ABSTRACT FROM AUTHOR]

In this paper, we studied the magnetic stability, structural, elastic and electronic properties of Ir2FeAl full Heusler compound in the regular phase (Cu2MnAl, prototype L2 1) , by using the first principle of density functional theory, with the generalized approximation of the GGA gradient. We found that the ferromagnetic state of Ir2FeAl is more stable than the nonmagnetic configuration at their lattice parameters equilibrium. This result was confirmed by the calculation of the cohesive energy. The stability is asserted by the elastic constants and the conditions of the mechanical stability criterion. The band structure and the calculated densities of states (DOS) of this alloy show a semi-metallic behavior. The ferromagnetic performance of Ir2FeAl is confirmed by the total magnetic moment of 4.28 μ B , where its major contribution comes from Fe atoms. We estimated the Debye temperature of Ir2FeAl from the average speed of sound. This is the first quantitative theoretical prediction of the elastic properties of the Ir2FeAl compound, and it still awaits experimental confirmation. [ABSTRACT FROM AUTHOR]

Complexes containing isolated dysprosocenium cations, [Dy(CpR)2][WCA] (CpR = substituted cyclopentadienyl, WCA = weakly coordinating anion), have recently emerged as leading examples of high-temperature single-molecule magnets (SMMs) due to a combination of the axial orientation and rigidity of the CpR rings. However, our understanding of the effects of transverse fields on the magnetic properties of [Dy(CpR)2]+ cations is underdeveloped. Here we investigate the impact of equatorially-bound WCAs via the synthesis of the Dy(III) bis-CpR complexes [Dy(Cpttt)2{AlCl[OC(CF3)3]3-κ-Cl}] (1) and [Dy(Cpttt)2{AlCl(C2H5)[OC(C6F5)3]2-κ-Cl}] (2), and their characterisation by single crystal XRD, elemental analysis, ATR-IR and NMR spectroscopy, and ab initio calculations. Despite the similarity of the Dy coordination spheres in 1 and 2 we find that their effective energy barriers to reversal of magnetisation are vastly different (Ueff = 886(17) cm−1 and 559(18) cm−1, respectively) and they both show waist-restricted magnetic hysteresis at 2 K. Together, these data provide fresh insights into the sensitivity of the magnetic properties of [Dy(CpR)2]+ cations to relatively weak equatorial interactions. [ABSTRACT FROM AUTHOR]

Three dinuclear dysprosium complexes 1–3 with structural formulas [Dy2(bptz)(tta)6]·2CH2Cl2 (1), [Dy2(H2bmtz)(tta)6] (2) and [Dy2(H2bmtz)(hfac)6(H2O)2] (3) (bptz = 3,6-di(2-pyridyl)-1,2,4,5-tetrazine, H2bmtz = 3,6-di(2-pyrimidyl)-1,4-dihydro-1,2,4,5-tetrazine, tta = 2-thenoyltrifluoroacetonate, hfac = hexafluoroacetylacetonate) were synthesized by the use of two tetrazine derivative ligands containing six and eight nitrogen atoms in combination with β-diketonate co-ligands, which are a good research platform to study the synergistic influence of the local coordination environment and magnetic interaction on magnetic relaxation. Complexes 1 and 2 possess the same peripheral co-ligands and nearly the same coordination environment (approaching an ideal triangular dodecahedron), but different multi-nitrogen bridges involving N6 (bptz) and N8 (H2bmtz) tetrazine derivatives. The structural difference leads to distinct magnetic relaxation properties with a hysteresis temperature of 2.5 K and 5.5 K at a rate of 200 Oe s−1 in 1 and 2, respectively, which is most likely due to the different magnetic coupling transmitted by H2bmtz and bptz in the direction close to the vertical magneto axis. Combined with a suitable local coordination environment, the energy barrier of complex 2 bridged by H2bmtz can reach three times that of complex 3. Considering the local ligand field, the important influence of this multi-nitrogen bridge transmitting magnetic coupling on the SMM properties is demonstrated with the aid of ab initio calculations. Also of note is that complexes 2 and 3 are the first reported lanthanide SMMs constructed from dihydro-tetrazine. [ABSTRACT FROM AUTHOR]

Dinuclear Ni(II)/Ce(III) complexes, namely [Ni(o-van-dap)Ce(H2O)(NO3)3] (1) and [Ni(H2O)2(o-van-dmdap)Ce(NO3)3] (2), were synthesized and chemically and spectroscopically characterized. Single crystal X-ray analyses revealed that in both 1 and 2 bicompartmental Schiff base-type ligands (o-van-dap)2− and (o-van-dmdap)2− are present, with neighbouring cis-N2O2 and O4 donor sets. The smaller N2O2 cavity is occupied by the Ni(II) ions while the larger O4 cavity contains a Ce(III) ion; both metal ions are linked via a pair of monoatomic O-bridges with the O atoms provided by deprotonated hydroxyl groups. In complex 1 the bridging unit within the Schiff base-type ligand is formed from two carbon atoms; consequently the central Ni(II) atom has a square-planar geometry, and is thus diamagnetic. In complex 2 the bridging unit within the structure of the ligand is composed of three carbon atoms yielding a larger cavity accommodating a paramagnetic, hexacoordinated Ni(II) atom, whose coordination sphere is completed by two axial aqua ligands. The Ce(III) atoms in both 1 and 2 are additionally coordinated by three chelating nitrato co-ligands resulting in coordination number 10 in 2, while another aqua ligand increases the coordination number of the Ce(III) atom in 1 to 11. Variable temperature dc magnetic studies of both 1 and 2 (2–300 K) corroborate the diamagnetism of the Ni(II) atom (S = 0) in 1 and paramagnetism of the Ni(II) atom (S = 1) in 2. The ac magnetic studies showed that both complexes 1 and 2 exhibit field induced slow magnetic relaxation. The obtained values of the energy barriers are Δ/kB = 24.1 K with τ0 = 6.96 × 10−8 s for 1, and Δ/kB = 9.88 K with τ0 = 5.36 × 10−7 s for 2. One-atomic elongation of the bridging unit in the bicompartmental ligand induces change of the magnetic character of the Ni(II) central atoms from S = 0 in 1 to S = 1 in 2, and this change leads to significant differences in the values of the respective Δ/kB parameters. Theoretical ab initio calculations for complexes 1 and 2 were performed to investigate their magnetic properties in detail. [ABSTRACT FROM AUTHOR]

This paper will focus on the comparative study of the structural, electronic, magnetic, optical, and thermoelectric properties of the two Heusler systems Ag2TiGa and Ag2VGa in the inverse L21 Hg2CuTi structure. Using the density functional theory‐based wien2k code, which implements the computational methods used in this study, namely GGA, GGA‐mBJ, GGA + U, and GGA + SOC (spin‐orbit coupling). The band structures show that all two structures studied are metallic. The spin density of states of Ag2VGa has evident spin splitting near the Fermi level, and the total magnetic moment of the Ag2VGa structure is 2.19 μB, which indicates that Ag2VGa is magnetic. The full‐Heusler Ag2VGa material can be used as spintronic materials due to their high spin polarization (about 50%). While Ag2TiGa has low polarization so it is bad electronically, but better thermoelectrically than Ag2VGa. So, the full‐Heusler Ag2TiGa material may also be considered as a potential candidate for thermoelectric applications at room temperature. Studies of the two new Heusler alloys may provide a theoretical reference for subsequent theoretical research and experimental synthesis of Ag‐based Heusler alloys. [ABSTRACT FROM AUTHOR]

In this paper, we investigate the solubility effects of Co in ZnO (Zn1−xCoxO, where x = 0, 0.03, 0.05, 0.1, 0.2, 0.25, 0.4, 0.8, and 1) by combining the results of perturbed angular correlation (PAC) spectroscopy using highly diluted 111Cd as probe nuclei and ab initio calculations based on spin-density functional theory (SDFT). This combined approach enables us to characterize the local structure around Cd ions, where, through PAC technique, it was possible to measure the EFG as a function of temperature and Co concentration and thereby monitor the changes in the structure and the Co solubility threshold in ZnO and the ZnO/CoO/Co3O4 mixed phase. The full-potential linear augmented plane wave plus local orbital (APW+lo) formalism were used here to describe the electronic structure of the supercells, including the atomic relaxations. These Ab initio calculations show an interesting behavior of the Cd and Co impurity levels in the band structure of ZnO, which explains the experimental results in terms of the origin of EFG and the evidence of ferromagnetic response. [ABSTRACT FROM AUTHOR]

Currently, there is rapid development of thermophysics of solids associated with the need to create models with a high degree of predictive reliability. This paper presents new approaches to solve relevant issues related to the study of heat transfer in semiconductors and dielectrics, mainly concerning nanostructures. The first of the considered tasks is the creation of a statistical model of the processes of interaction of heat carriers, phonons, with the rough surfaces of solids. For the first time, the authors propose a method based on the statistics of the slopes of the profile of a random surface. The calculation results are the mean free paths of phonon between the opposite boundaries of the sample, which are necessary for calculating the effective thermal conductivity in the ballistic and diffusion–ballistic regime of heat transfer, depending on the roughness parameters. The second task is to develop methods for calculating the processes of heat transfer through the contact surfaces of solids. We are able to show that, taking into account the phonon dispersion and the corresponding restrictions on the frequency values, the modified acoustic mismatch model for calculating Kapitza resistance can be extended to temperatures above 300 K. Previously, the limit of applicability of this method was considered to be a temperature of 30 K. Moreover, the proposed method is also generalized to the case of rough interfaces. The third task is a new approach to determine the thermal conductivity of solids. The authors develop a method of direct Monte Carlo simulation of phonon kinetics with strict consideration of their interaction due to the direct use of the laws of conservation of energy and quasi-momentum. The calculations of the thermal conductivity coefficient for pure silicon in the temperature range from 100 to 300 K show close agreement with the experiment and ab initio calculations of other authors, and also allow considering in details the kinetics of phonons. [ABSTRACT FROM AUTHOR]

This paper highlights the use and applications of the energy loss function (ELF) for materials analysis by using electron energy loss spectroscopy (EELS). The basic Drude–Lindhart theory of the ELF is briefly presented along with reference to reflection electron energy loss (REELS) data for several dielectric materials such as insulating high-k binary oxides and semiconductors. Those data and their use are critically discussed. A comparison is made to the available ab initio calculations of the ELF for these materials. Experimental, high-resolution TEM-EELS data on Si, SiC, and CeO2 obtained using a high-resolution, double-Cs-corrected transmission electron microscope are confronted to calculated spectra on the basis of the ELF theory. Values of plasmon energies of these three dielectric materials are quantitatively analyzed on the basis of the simple Drude's free electron theory. The effects of heavy ion irradiation on the TEM-EELS spectra of Si and SiC are addressed. In particular, the downward shifts of plasmon peaks induced by radiation damage and the subsequent amorphization of Si and SiC are discussed. TEM-EELS data of CeO2 are also analyzed with respect to the ELF data and with comparison to isostructural ZrO2 and PuO2 by using the same background and with reference to ab initio calculations. [ABSTRACT FROM AUTHOR]

In several recent years, a significant progress has been made in atomistic simulation of materials, involving the application of machine learning methods to constructing classical interatomic interaction potentials. These potentials are many-body functions with a large number of variable parameters whose values are optimized with the use of energies and forces calculated for various atomic configurations by ab initio methods. In the present paper a machine learning potential is developed on the basis of deep neural networks (DP) for Al–Cu alloys, and the accuracy and performance of this potential is compared with the embedded atom potential. The analysis of the results obtained implies that the DP provides a sufficiently high accuracy of calculation of the structural, thermodynamic, and transport properties of Al–Cu alloys in both solid and liquid states over the entire range of compositions and a wide temperature interval. The accuracy of the embedded atom model (EAM) in calculating the same properties is noticeably lower on the whole. It is demonstrated that the application of the potentials based on neural networks to the simulation on modern graphic processors allows one to reach a computational efficiency on the same order of magnitude as those of the embedded atom calculations, which at least four orders of magnitude higher than the computational efficiency of ab initio calculations. The most important result is that about the possibility of application of DP parameterized with the use of configurations corresponding to melts and perfect crystals to the simulation of structural defects in crystals and interphase surfaces. [ABSTRACT FROM AUTHOR]

This work presents a hydrothermal-based facile method for synthesizing ZnFe2O4, whose size can be controlled with the concentration of sodium acetate used as a fuel and its physical changes at nanoscales when exposed to two different gases. The structural, morphological, compositional, and electronic properties of the synthesized samples are also presented in this paper. The crystal structure of the synthesized samples was determined using an X-ray Diffractometer (XRD). The results revealed fluctuations in the size, lattice parameter, and strain in the nanoparticles with increasing the concentration of sodium acetate. Field-Emission Scanning Electron Microscopy (FESEM) was used to determine synthesized materials' morphology and particle size. It revealed that the particles possessed approximately spherical morphology whose size decreased significantly with the increasing amount of sodium acetate. Transmission Electron Microscopy (TEM) was utilized to determine the structure, morphology, and elemental distributions in particles at the nanoscale, and it confirmed the findings of XRD and FESEM analyses. The high-resolution TEM (HRTEM) imaging analysis of the nanoparticles in our studied samples revealed that the particles predominantly possessed (001) type facets. X-ray photoelectron spectroscopy (XPS) and core-loss electron energy loss spectroscopy (EELS) showed an increasing fraction of Fe2+ with the decreasing size of the particles in samples. The Brunauer, Emmett, and Tellers (BET) analysis of samples revealed a higher surface area as the particle size decreases. In addition, the determined surface area and pore size values are compared with the literature, and it was found that the synthesized materials are promising for gas-sensing applications. The ab initio calculations of the Density of States (DOS) and Band structure of (001) surface terminating ZnFe2O4 were carried out using Quantum Espresso software to determine the bandgap of the synthesized samples. They were compared to their corresponding experimentally determined bandgap values and showed close agreement. Finally, in-situ TEM measurement was carried out on one of the four studied samples with robust properties using Ar and CO2 as reference and target gases, respectively. It is concluded from the presented study that the size reduction of the ZnFe2O4 nanoparticles (NPs) tunes the bandgap and provides more active sites due to a higher concentration of oxygen vacancies. The in-situ TEM showed us a nanoscale observation of the change in one of the crystal structure parameters. The d spacing of ZnFe2O4 NPs showed a noticeable fluctuation, reaching more than 5% upon exposure to CO2 and Ar gases. [ABSTRACT FROM AUTHOR]

This paper portrays the solution-phase dynamics as copper(II) and ethylenediamine explore a multitude of different complexes. The data from five spectrophotometric titrations were globally analysed, evidencing four predominant species ([Cu]2+, [Cu(en-N,N')]2+, [Cu(en-N,N')2]2+, [Cu(en-N)4]2+) along with their molar absorptivity curves and associative binding constants. The data also seem to support a fifth species, [Cu2(µ-en-N,N')]4+, in which ethylenediamine bridges two Cu(II) centres. The thermodynamic stability of all five species is corroborated by ab initio computational calculations. The potential existence of [Cu(en-N)4]2+ highlights the suprachelate effect – going beyond the chelate effect – where multidenticity is overtaken by monodenticity. Such dangling multidentate ligands are available to bind to additional metal centres and thus build towards self-assembling supramolecules. [ABSTRACT FROM AUTHOR]

This paper studies the mechanism of electrochemically induced carbon–bromine dissociation in 1-Br-2-methylnaphalene in the reduction regime. In particular, the bond dissociation of the relevant radical anion is disassembled at a molecular level, exploiting quantum mechanical calculations including steady-state, equilibrium and dissociation dynamics via dynamic reaction coordinate (DRC) calculations. DRC is a molecular-dynamic-based calculation relying on an ab initio potential surface. This is to achieve a detailed picture of the dissociation process in an elementary molecular detail. From a thermodynamic point of view, all the reaction paths examined are energetically feasible. The obtained results suggest that the carbon halogen bond dissociates following the first electron uptake follow a stepwise mechanism. Indeed, the formation of the bromide anion and an organic radical occurs. The latter reacts to form a binaphthalene intrinsically chiral dimer. This paper is respectfully dedicated to Professors Anny Jutand and Christian Amatore for their outstanding contribution in the field of electrochemical catalysis and electrosynthesis. [ABSTRACT FROM AUTHOR]

This paper is a detailed review of the chemistry of medium-size reactive systems using the following hydrogen abstraction reactions with ethane, X + C2H6 → HX + C2H5; X ≡ H, F(2P), Cl(2P), O(3P) and OH, and focusing attention mainly on the theoretical developments. These bimolecular reactions range from exothermic to endothermic systems and from barrierless to high classical barriers of activation. Thus, the topography of the reactive systems changes from reaction to reaction with the presence or not of stabilized intermediate complexes in the entrance and exit channels. The review begins with some reflections on the inherent problems in the theory/experiment comparison. When one compares kinetics or dynamics theoretical results with experimental measures, one is testing both the potential energy surface describing the nuclei motion and the kinetics or dynamics method used. Discrepancies in the comparison may be due to inaccuracies of the surface, limitations of the kinetics or dynamics methods, and experimental uncertainties that also cannot be ruled out. The paper continues with a detailed review of some bimolecular reactions with ethane, beginning with the reactions with hydrogen atoms. The reactions with halogens present a challenge owing to the presence of stabilized intermediate complexes in the entrance and exit channels and the influence of the spin-orbit states on reactivity. Reactions with O(3P) atoms lead to three surfaces, which is an additional difficulty in the theoretical study. Finally, the reactions with the hydroxyl radical correspond to a reactive system with ten atoms and twenty-four degrees of freedom. Throughout this review, different strategies in the development of analytical potential energy surfaces describing these bimolecular reactions have been critically analyzed, showing their advantages and limitations. These surfaces are fitted to a large number of ab initio calculations, and we found that a huge number of calculations leads to accurate surfaces, but this information does not guarantee that the kinetics and dynamics results match the experimental measurements. [ABSTRACT FROM AUTHOR]

Coupled-channel two-particle systems bound by a harmonic trap are discussed in the present paper. Under assumption of short-range interactions, the formula that relates the energy levels of such trapped systems to phase shifts and inelasticity of coupled-channel reactions can be obtained in a closed form. The present paper may set some groundworks toward extracting scattering amplitudes of inelastic nuclear reactions from ab initio calculations of discrete levels of many-nucleon systems in a harmonic trap. [ABSTRACT FROM AUTHOR]

Lithium–magnesium fluorophosphate with the formula Li9Mg3[PO4]4F3 has recently been proposed as a new thermoluminescent material capable of storing ionizing radiation energy and emitting photons after additional thermal stimulation. Pure and sodium-doped fluorophosphates were obtained by microwave-assisted synthesis. Using X-ray and neutron diffraction methods, it was shown that sodium occupies only one of the three nonequivalent lithium positions. This conclusion was confirmed by a MAS NMR study and ab initio calculations. A significant increase in the thermoluminescence intensity of sodium-containing fluorophosphates in comparison to the undoped compound was found. Analysis of the kinetic parameters obtained from glow curves showed that they are similar for the undoped and sodium-doped samples. This indicates that the addition of sodium does not result in the emergence of novel types of traps, but rather in a change in their number. The effect of sodium on the formation of intrinsic defects, which can be responsible for the enhanced thermoluminescence, is considered using ab initio modelling. [ABSTRACT FROM AUTHOR]

Context: 1,1- and 1,2-ethenedithiol are elusive systems that could potentially exist in interstellar space, similar to analogous diols. In this paper, we investigate the structure, stability, and bonding characteristics of these compounds as well as the ions produced by protonation, deprotonation, or simple ionization processes. 1,2-ethenedithiol has two isomers, Z and E, with the most stable conformer being syn-anti for the Z isomer and anti-anti for the E isomer. However, the energy gaps between the different conformers are never larger than 6 kJ·mol−1. For 1,1-ethenedithiol, the global minimum is the syn-anti conformer. The vertical and adiabatic ionization processes as well as the intrinsic basicities and acidities of these families of compounds were analyzed and compared with those of the corresponding diols previously reported in the literature. This comparison revealed not only the numerical differences in these thermodynamic properties but also distinct trends between the two families of compounds. Methods: State-of-the-art G4 ab initio calculations were employed to calculate the structures and total energies of the systems under investigation. The QTAIM, ELF, and NBO approaches were used to analyze the electron density of all the neutral and charged systems included in our study. Van der Waals contributions, when relevant, were analyzed by locating regions of low reduced density gradient(s) using the NCIPLOT approach. [ABSTRACT FROM AUTHOR]

The electronic structure and related electronic properties of two novel isostructural octacyanometallates Cd2(H2O)4[MoIV(CN)8]·2H2O and Cd2(H2O)4[WIV(CN)8]·2H2O are described from a combined experimental and computational approach. The impact that the octacoordinated heavy metals W and Mo have on the electronic structure and optical response of isostructural materials whose electronic properties strongly depend on the crystal structure is discussed. It is found that the effect of the polarization power of the metal centers, combined with the ligand field of cyanos, produces considerable changes in the electronic structure and, consequently, in the band gap energy. The ab initio calculations, which were performed with generalized gradient PBE and hybrid HSE06 density functionals, accurately reproduce the electronic structure of [Mo(CN)8]4− and [W(CN)8]4− building units, revealing that the electronic transitions associated with the band gap energy have an origin in the charge transfer phenomena of metal to ligand nature. Moreover, the optical band gap transitions have an allowed indirect behavior in the Γ → M → D direction which is associated with the (x2 − y2) → π* transition. The allowed direct and indirect (experimental and theoretical) band gap energies together with the exciton effective masses are reported. [ABSTRACT FROM AUTHOR]

The degradation of water bodies caused by organic pollutants from industrial wastewater discharge has made it necessary to develop new functional materials like hydrophobic–oleophilic materials that can efficiently remediate water. It is factual that many of the synthetic methods for creating hydrophobic–oleophilic materials involve the use of toxic or harmful reactants, such as fluorine or sulfur compounds. However, these methods often have significant drawbacks, including being hazardous to the environment, expensive, and complex to utilize. Therefore, there is an urgent need to develop a hydrophobic/oleophilic material that is non-toxic and eco-friendly in order to overcome the existing drawbacks. In this regard, we have proposed a modest and eco-friendly approach for constructing a hydrophobic–oleophilic Ph-POSS@HKUST-1 composite material by solution-assisted self-assembly for the conversion of hydrophilic HKUST-1 into hydrophobic HKUST-1 for separation applications. The incorporation of fluorine-free, low surface energy and hydrophobic POSS into HKUST-1 increased the hydrophobicity and oleophilicity of the system. The synthesized Ph-POSS@HKUST-1 composite material has been thoroughly characterized through FT-IR, PXRD, HR-SEM, BET, and thermogravimetric analysis. It has been observed that the material exhibits a contact angle of 137 ± 4° and shows high selectivity and absorption capacity towards organic solvents and oils from water mixtures. Concurrently, the Ph-POSS@HKUST-1@PDA@sponge has been effectively utilized for the separation of solvents and oils and it has shown more than 95% separation efficiency for up to 15 cycles. It is interesting to note that Ph-POSS@HKUST-1 and the Ph-POSS@HKUST-1@PDA@sponge have outstanding stability in abrasive chemical environments which is due to the presence of a mechanically and chemically stable inorganic–organic hybrid POSS nanocage. In addition, ab initio and DFT calculations elicit that the Ph-POSS@HKUST-1 composite is stabilized through π⋯π stacking instead of the C–H⋯π mode of interaction at the HKUST-1⋯Ph-POSS interface. Further electron density features confirm the interfacial interaction at the interface. Our latest research has led us to propose an eco-friendly and non-toxic hybrid composite material for efficiently tackling the issue of organic solvent and oil pollution in water mixtures. [ABSTRACT FROM AUTHOR]

Four mononuclear CoII complexes of formula [Co(L)(SCN)2(CH3OH)0.5(H2O)0.5]·1.5H2O·0.75CH3OH (1), [Co(L1)Cl2]·H2O·2CH3CN (2), [Co(L1)(SCN)2]·1.5H2O·CH3OH (3) and [Co(L1)]ClO4·2CH3OH (4) were prepared from the N6-tripodal Schiff base ligands (S)P[N(Me)N＝C(H)2-Q]3 (L) and (S)P[N(Me)N＝C(H)1-ISOQ]3 (L1), where Q and ISOQ represent quinolyl and isoquinolyl moieties, respectively. In 1, the L ligand does not coordinate to the CoII ion in a tripodal manner but using a new N,N,S tridentate mode, which is due to the fact that the N6-tripodal coordination promotes a strong steric hindrance between the quinolyl moieties. However, L1 can coordinate to the CoII ions either in a tripodal manner using CoII salts with poorly coordinating anions to give 4 or in a bisbidentate fashion using CoII salt-containing medium to strongly coordinating anions to afford 2 and 3. In the case of L1, there is no steric hindrance between ISOQ moieties after coordination to the CoII ion. The CoII ion exhibits a distorted octahedral geometry for compounds 1–3, with the anions in cis positions for the former and in trans positions for the two latter compounds. Compound 4 shows an intermediate geometry between an octahedral and trigonal prism but closer to the latter one. DC magnetic properties, HFEPR and FIRMS measurements and ab initio calculations demonstrate that distorted octahedral complexes 1–3 exhibit easy-plane magnetic anisotropy (D > 0), whereas compound 4 shows large easy-axis magnetic anisotropy (D < 0). Comparative analysis of the magneto-structural data underlines the important role that is played not only by the coordination geometry but also the electronic effects in determining the anisotropy of the CoII ions. Compounds 2–3 show a field-induced slow relaxation of magnetization. Despite its large easy-axis magnetic anisotropy, compound 4 does not show significant slow relaxation (SMR) above 2 K under zero applied magnetic fields, but its magnetic dilution with ZnII triggers SMR at zero field. Finally, it is worth remarking that compounds 2–4 show smaller relaxation times than the analogous complexes with the tripodal ligand bearing in its arms pyridine instead of isoquinoline moieties, which is most likely due to the increase of the molecular size in the former one. [ABSTRACT FROM AUTHOR]

Among the recent developments in metal–organic frameworks (MOFs), porous two-dimensional (2D) MOFs have garnered attention due to providing key technical supports, important energy-saving measures and precise chemical sensors for the green and sustainable society. Herein, two rare porous 2D Dy3+ MOFs, namely [Dy4L6(DMA)2(H2O)3]·7DMA (1, DMA = N,N-dimethylacetamide) and [Dy2L3(DMF)2]·DMF (2, DMF = N,N-dimethylformamide), have been successfully synthesized from reaction with 4,4′-(1,2-diphenylethene-1,2-diyl) dibenzoic acid (H2L) under different solvent systems. The main distinctions between the crystal structures of 1 and 2 arise from the differing solvent molecules residing within the pores which interact with the surrounding frameworks. These effects lead to different sizes of 1D channels. Importantly, different solvents of coordinated/free DMA molecules in 1 and DMF molecules in 2 induce the conversion of magnetic dynamics. Compound 1 exhibits obvious slow magnetic relaxation behavior under 0 Oe dc field, while zero-field out-of-phase signals of 2 exhibit no peaks in the whole temperature range. Compound 1 was magnetically characterized as a new example that the slow magnetic relaxation process can be observed in a 2D Dy3+ layer with 1D channels. Theoretical analysis based on ab initio calculation provides interpretations of magnetic observation. Additionally, compounds 1 and 2 have been tested as efficient fluorescent sensors for Fe3+ ions with high selectivity and sensitivity. The fluorescence quenching of 1 and 2 was demonstrated by an approximately 90% reduction in the emission intensity upon binding to Fe3+ ions. The emission intensities of 1 and 2 at 464 nm and 443 nm have shown linear responses to Fe3+ ion concentration with detection limits of 4.51 × 106 ppb and 6.90 × 106 ppb. [ABSTRACT FROM AUTHOR]

Context: One of the crucial issues related to machine learning potentials is the formation of representative dataset. For multicomponent systems, it is a general methodology to scan the composition range with a certain step. However, there is a lack of information on the compositional transferability of machine learning potentials. In this paper, we extend the knowledge in this area by studying the transferability of deep learning potential over the range of compositions of LiCl–KCl molten mixtures. The training dataset was formed using only the near-eutectic composition of 60% LiCl–40% KCl. Then, we tested the ability of the model to predict physicochemical properties of the melts far from the reference composition. It was found that for the composition range from 0 to 100% of LiCl, the calculated properties concur closely with those of other studies and ab initio calculations. Therefore, the model shows prominent non-intuitive compositional transferability. Moreover, the solid states and solid–liquid coexistence were reproduced. The calculated melting temperatures of LiCl and KCl show the errors of 6.6% and 0.4%, respectively. We argue that such good transferability stems from the local structure configurations that are typical both for pure LiCl and for pure KCl which are implicitly presented in the training dataset because of local fluctuations in composition. Methods: To collect the data for the initial dataset, density functional theory was employed. Then, the DeePMD package was used to train a neural network potential. To calculate the properties of the melts, standard equilibrium and non-equilibrium molecular dynamic approaches were utilized. [ABSTRACT FROM AUTHOR]

In this paper, we studied the magnetism of Fe2N, using the ab initio and Monte Carlo studies. The magnetic moment and the exchange couplings are deduced by ab initio calculations. The obtained density of states is not symmetrical with respect to the axis of energy proving the ferromagnetic character of this compound. Any gap energy, at the Fermi level, is found confirming the metallic character of this compound. The Hamiltonian of this system consists of several physical parameters. Both the magnetic entropy and the maximum magnetic entropy are obtained. The relative cooling power and the magnetic hysteresis cycle are illustrated. The transition temperature TC value has been deduced and found to be about 252.01 K. This value is in good agreement with the experimental results presented. Also, we found that the magnetizations decrease rapidly to zero with increasing temperature. This is due to the ferromagnetic-paramagnetic phase transition caused by thermal energy. [ABSTRACT FROM AUTHOR]

This paper presents an improved theoretical view of ab initio thermodynamics for polar GaN surfaces under gallium-rich conditions. The study uses density functional theory (DFT) calculations to systematically investigate the adsorption of gallium atoms on GaN polar surfaces, starting from the clean surface and progressing to the metallic multilayer. First principles phonon calculations are performed to determine vibrational free energies. Changes in the chemical potential of gallium adatoms are determined as a function of temperature and surface coverage. Three distinct ranges of Ga coverage with very low, medium, and high chemical potential are observed on the GaN(000-1) surface, while only two ranges with medium and high chemical potential are observed on the GaN(000-1) surface. The analysis confirms that a monolayer of Ga adatoms on the GaN(000-1) surface is highly stable over a wide range of temperatures. For a second adlayer at higher temperatures, it is energetically more favorable to form liquid droplets than a uniform crystalline adlayer. The second Ga layer on the GaN(0001) surface shows pseudo-crystalline properties even at a relatively high temperature. These results provide a better thermodynamic description of the surface state under conditions typical for molecular beam epitaxy and offer an interpretation of the observed growth window. [ABSTRACT FROM AUTHOR]

Based on an analytical full‐dimensional potential energy surface (PES), named PES‐2022, fitted to high‐level ab initio calculations previously developed by our group and specifically developed to describe this polyatomic reactive process, an exhaustive kinetics analysis was performed in the temperature range 50–2000 K, that is, interstellar, atmospheric and combustion conditions. Using the competitive canonical unified theory with multidimensional tunneling corrections of small curvature, CCUS/SCT, and low‐ and high‐pressure limit (LPL and HPL) models, in this wide temperature range we found that the overall rate constants increase with temperature at T > 300 K and T < 200 K, showing a V‐shaped temperature dependence, reproducing the experimental evidence when the HPL model was used. The increase of the rate constant with temperature at low temperatures was due to the strong contribution of the tunneling factor. The title reaction evolves by two paths, H2O + CH2OH (R1) and H2O + CH3O (R2), and the branching ratio analysis showed that the R2 path was dominant at T < 200 K while the R1 path dominated at T > 300 K, with a turnover temperature of ∼260 K, in agreement with previous theoretical estimations. Three kinetics isotope effects (KIEs), 13CH3OH, CH318OH, and CD3OH, were theoretically studied, reproducing the experimental evidence. The kinetics analysis in the present paper together with the dynamics study previously reported showed the capacity of the PES‐2022 to understand this important chemical process. [ABSTRACT FROM AUTHOR]

Context. Carbon monosulphide (CS) is among the few sulphur-bearing species that have been widely observed in all environments, including in the most extreme, such as diffuse clouds. Moreover, CS has been widely used as a tracer of the gas density in the interstellar medium in our Galaxy and external galaxies. Therefore, a complete understanding of its chemistry in all environments is of paramount importance for the study of interstellar matter. Aims. Our group is revising the rates of the main formation and destruction mechanisms of CS. In particular, we focus on those involving open-shell species for which the classical capture model might not be sufficiently accurate. In this paper, we revise the rates of reactions CH + S → CS + H and C2 + S → CS + C. These reactions are important CS formation routes in some environments such as dark and diffuse warm gas. Methods. We performed ab initio calculations to characterize the main features of all the electronic states correlating to the open shell reactants. For CH+S, we calculated the full potential energy surfaces (PESs) for the lowest doublet states and the reaction rate constant with a quasi-classical method. For C2+S, the reaction can only take place through the three lower triplet states, which all present deep insertion wells. A detailed study of the long-range interactions for these triplet states allowed us to apply a statistic adiabatic method to determine the rate constants. Results. Our detailed theoretical study of the CH + S → CS + H reaction shows that its rate is nearly independent of the temperature in a range of 10–500 K, with an almost constant value of 5.5 × 10−11 cm3 s−1 at temperatures above 100 K. This is a factor of about 2–3 lower than the value obtained with the capture model. The rate of the reaction C2 + S → CS + C does depend on the temperature, and takes values close to 2.0 × 10−10 cm3 s−1 at low temperatures, which increase to ~ 5.0 × 10−10 cm3 s−1 for temperatures higher than 200 K. In this case, our detailed modeling - taking into account the electronic and spin states – provides a rate that is higher than the one currently used by factor of approximately 2. Conclusions. These reactions were selected based on their inclusion of open-shell species with many degenerate electronic states, and, unexpectedly, the results obtained in the present detailed calculations provide values that differ by a factor of about 2–3 from the simpler classical capture method. We updated the sulphur network with these new rates and compare our results in the prototypical case of TMC1 (CP). We find a reasonable agreement between model predictions and observations with a sulphur depletion factor of 20 relative to the sulphur cosmic abundance. However, it is not possible to fit the abundances of all sulphur-bearing molecules better than a factor of 10 at the same chemical time. [ABSTRACT FROM AUTHOR]

Continuing Q-band (31–50 GHz) integrations on IRC +10216 with the Yebes 40 m telescope have now reached sub-millikelvin noise with hundreds of new lines arising above an average 3σ detection limit of 0.71 mK (as low as 0.45 mK in the lower frequency end). The recent discovery of the C7N− anion and the relatively large abundance of the HC9N member of the cyanopolyyne family opens the door for searching in the data for harmonically related series of lines belonging to singlet species, with intensities close to the detection limit, that could belong to heavier anions. One such series has been found with rotational quantum numbers from J = 52 − 51 up to J = 74 − 73, with at least 15 distinguishable features clearly detected as isolated or partly blended. There are two main candidates for the carriers of the series: C9N− and/or C10H−, for which our high-level-of-theory ab initio calculations predict a quite compatible rotational constant of ~300 MHz. In this paper we discuss, based on our ab initio calculations and also on chemical models, which of these two candidates is the most likely carrier. There is more evidence for the C10H− candidate. It would be, to date, the heaviest anion discovered in space through a series of detected individual lines. [ABSTRACT FROM AUTHOR]