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A simplified theoretical description of multiple-quantum excitation and mixing for nuclear magnetic resonance of half-integer quadrupolar nuclei is presented. The approach recasts the multiple-quantum nutation behavior in terms of reduced excitation and mixing curves through a scaling of the first-order offset frequency by the quadrupolar coupling constant. The two-dimensional correlation of the static first-order anisotropic line shape to the second-order anisotropic magic-angle-spinning (MAS) line shape is utilized to transform the three-dimensional integral over the three Euler angles into a single integral over the dimensionless first-order offset parameter. These transformations lead to a highly efficient algorithm for simulating the multiple-quantum (MQ)-MAS spectrum for arbitrary excitation and mixing radio frequency (RF) field strengths, pulse durations, and MAS rates within the static limit approximation, which is defined in terms of the rotation period, pulse duration, RF field strength, and quadrupolar coupling parameters. This algorithm enables a more accurate determination of the relative site populations and quadrupolar coupling parameters in a least-squares analysis of MQ-MAS spectra. Furthermore, this article examines practical considerations for eliminating experimental artifacts and employing affine transformations to improve least-squares analyses of MQ-MAS spectra. The optimum ratio of RF field strength to the quadrupolar coupling constant and the corresponding pulse durations that maximize sensitivity within experimental constraints are also examined. [ABSTRACT FROM AUTHOR]

Several N-heterocyclic carbenes (NHCs) are experimentally observed upon the addition of muonium (Mu), and the hyperfine coupling constants (HFCCs) of muon are measured. Theoretical investigation of Mu has been challenging due to significant quantum effects. Herein, we performed an ab initio path integral molecular dynamics (PIMD) simulation, which accurately considers multi-dimensional quantum effects, to theoretically investigate muoniated 1,3-dihydro-2H-imidazole-2-ylidene (Mu-IY). Our findings indicate that quantum effects have two contradictory contributions: the quantum effect of bond vibrations increases the HFCC values, whereas that of out-of-plane angular vibrations decreases the HFCC values. Moreover, we show that the HFCC values of other NHCs can be predicted without the PIMD simulations by applying the structural changes caused by the quantum effect derived from the PIMD simulations of Mu-IY. [ABSTRACT FROM AUTHOR]

Fluctuations in energy gap and coupling constants between chromophores can play an important role in absorption and energy transfer across a collection of two-level systems. In photosynthesis, light-induced quantum coherence can affect the efficiency of energy transfer to the designated "trap" state. Theoretically, the interplay between fluctuations and coherence has been studied often, employing either a Markovian or a perturbative approximation. In this study, we depart from these approaches to incorporate memory effects by using Kubo's quantum stochastic Liouville equation. We introduce the effects of decay of the created excitation (to the ground state) on the desired propagation and trapping that provides a direction of flow of the excitation. In the presence of light-induced pumping, we establish a relation between the efficiency, the mean survival time, and the correlation decay time of the bath-induced fluctuations. A decrease in the steady-state coherence during the transition from the non-Markovian regime to the Markovian limit results in a decrease in efficiency. As in the well-known Haken–Strobl model, the ratio of the square of fluctuation strength to the rate plays a critical role in determining the mechanism of energy transfer and in shaping the characteristics of the efficiency profile. We recover a connection between the transfer flux and the imaginary part of coherences in both equilibrium and excited bath states, in both correlated and uncorrelated bath models. We uncover a non-monotonic dependence of efficiency on site energy heterogeneity for both correlated and uncorrelated bath models. [ABSTRACT FROM AUTHOR]

Two-dimensional (2D) Janus transition metal dichalcogenides MXY manifest novel physical properties owing to the breaking of out-of-plane mirror symmetry. Recently, the 2H phase of MoSH has been demonstrated to possess intrinsic superconductivity, whereas the 1T phase exhibits a charge density waves state. In this paper, we have systematically studied the stability and electron–phonon interaction characteristics of MoSLi. Our results have shown that both the 2H and 1T phases of MoSLi are stable, as indicated by the phonon spectrum and the ab initio molecular dynamics. However, the 1T phase exhibits an electron–phonon coupling constant that is twice as large as that of the 2H phase. In contrast to MoSH, the 1T phase of MoSLi exhibits intrinsic superconductivity. By employing the ab initio anisotropic Migdal-Eliashberg formalism, we have revealed the two-gap superconducting nature of 1T-MoSLi, with a transition temperature (Tc) of 14.8 K. The detailed analysis indicates that the superconductivity in 1T-MoSLi primarily originates from the interplay between the vibration of the phonon modes in the low-frequency region and the dz2 orbital. These findings provide a fresh perspective on superconductivity within Janus structures. [ABSTRACT FROM AUTHOR]

The Skyrmion Hall Effect (SkHE) observed in ferromagnetic and ferrimagnetic (FI) skyrmions traveling due to a spin-polarized current can be a problematic issue when it comes to technological applications. By investigating the properties of FI skyrmions in racetracks through computational simulations, we have described the nature of their movement based on the relative values of the exchange, Dzyaloshinskii–Moriya, and anisotropy coupling constants. Beyond that, using a design strategy, a magnetic channel-like nano-device is proposed in which a spin-polarized current protocol is created to successfully control the channel on which the skyrmion will travel without the adverse SkHE. Additionally, a simple adjustment in the current strength can modify the skyrmion position sideways between different parallel channels in the nanostripe. [ABSTRACT FROM AUTHOR]

The escape dynamics of sticky particles from textured surfaces is poorly understood despite importance to various scientific and technological domains. In this work, we address this challenge by investigating the escape time of adsorbates from prevalent surface topographies, including holes/pits, pillars, and grooves. Analytical expressions for the probability density function and the mean of the escape time are derived. A particularly interesting scenario is that of very deep and narrow confining spaces within the surface. In this case, the joint effect of the entrapment and stickiness prolongs the escape time, resulting in an effective desorption rate that is dramatically lower than that of the untextured surface. This rate is shown to abide a universal scaling law, which couples the equilibrium constants of adsorption with the relevant confining length scales. While our results are analytical and exact, we also present an approximation for deep and narrow cavities based on an effective description of one-dimensional diffusion that is punctuated by motionless adsorption events. This simple and physically motivated approximation provides high-accuracy predictions within its range of validity and works relatively well even for cavities of intermediate depth. All theoretical results are corroborated with extensive Monte Carlo simulations. [ABSTRACT FROM AUTHOR]

The ground state of 3d1 MnO42− was studied by density functional theory (DFT) and complete active space self-consistent field (CASSCF) methods in terms of a variety of molecular point group structures to ascertain the site and Jahn–Teller (JT) distortion effect. Modeling results from UB3LYP/6-31+G(d) calculations with natural bond orbital analysis show the four Mn–O bonds are coordinate covalent. The one-electron matrix elements from CASSCF(AILFT) (ab initio ligand field theory) with a second order perturbation treatment were used to calculate the parameters of the angular overlap model. These allowed the calculation of JT stabilization energies and first and second order JT coupling constants for MnO42− with C2v and D2d symmetry. Absorption spectra and excited state transition energies were calculated assuming the lattice distorted geometry was C2v with time-dependent DFT (TDDFT) using the unrestricted coulomb-attenuating UCAM-B3LYP density functional and with the spin-adapted spin-flip DFT using the UBH&HLYP density functional, both with the AUG-CC-PVTZ basis set. The mean absolute deviation of the calculations from experimental excited states for the ligand field and ligand-to-metal charge transfer (LMCT) bands was better than 0.1 eV. Several new assignments for LMCT excited states were made on the basis of the TDDFT excitation results. [ABSTRACT FROM AUTHOR]

Cyclopropylchloromethyldifluorosilane, c-C3H5SiF2CH2Cl, has been synthesized, and its rotational spectrum has been recorded by chirped-pulse Fourier transform microwave spectroscopy. The spectral analysis of several isotopologues indicates the presence of two distinct conformations in the free-jet expansion, which are interconvertible through a rotation of the chloromethyl group. A partial substitution structure is presented for the lower energy conformation and is compared to the equilibrium structure obtained from quantum chemical calculations. Additionally, the presence of the chlorine nucleus leads to the rotational transitions splitting into multiple hyperfine components and χaa, a measure of the electric field gradient along the a axis, is unusually small at merely +0.1393(73) MHz. Various common ab initio and density functional theory methods fail to predict good quadrupole coupling constants (in the principal axis system) that adequately reproduce the observed hyperfine splitting, although diagonalizing the quadrupole coupling tensor from the principal axis system into a nucleus-centered axis system reveals that, overall, these methods calculate reasonably the electric field gradient about the chlorine nucleus. Finally, a total of nine electric dipole forbidden, quadrupole allowed transitions are observed in the rotational spectra of the parent species of the higher energy conformation and the 37Cl isotopologue of the lower energy conformation. These include those of x-type (no change in parity of Ka or Kc), which, to our knowledge, is the first time such transitions have been observed in a chlorine-containing molecule. [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]

The scattering of H by I is a prototypical model system for light-heavy scattering in which relativistic coupling effects must be taken into account. Scattering calculations depend strongly on the accuracy of the potential energy surface (PES) model. The methodology to obtain such an accurate PES model suitable for scattering calculations is presented, which includes spin–orbit (SO) coupling within the Effective Relativistic Coupling by Asymptotic Representation (ERCAR) approach. In this approach, the SO coupling is determined only for the atomic states of the heavy atom, and the geometry dependence of the SO effect is accounted for by a diabatization with respect to asymptotic states. The accuracy of the full model, composed of a Coulomb part and the SO model, is achieved in the following ways. For the SO model, the extended ERCAR approach is applied, which accounts for both intra-state and inter-state SO coupling, and an extended number of diabatic states are included. The corresponding coupling constants for the SO operator are obtained from experiments, which are more accurate than computed values. In the Coulomb Hamiltonian model, special attention is paid to the long range behavior and accurate c6 dispersion coefficients. The flexibility and accuracy of this Coulomb model are achieved by combining partial models for three different regions. These are merged via artificial neural networks, which also refine the model further. In this way, an extremely accurate PES model for hydrogen iodide is obtained, suitable for accurate scattering calculations. [ABSTRACT FROM AUTHOR]

[Display omitted] In addition to the pressurized high-temperature superconductivity, bilayer and trilayer nickelate superconductors La n +1 Ni n O 3 n +1 (n = 2 and 3) exhibit many intriguing properties at ambient pressure, such as orbital-dependent electronic correlation, non-Fermi liquid behavior, and density-wave transitions. Here, using ultrafast reflectivity measurement, we observe a drastic difference between the ultrafast dynamics of the bilayer and trilayer nickelates at ambient pressure. We observe a coherent phonon mode in La 4 Ni 3 O 10 involving the collective vibration of La, Ni, and O atoms, which is absent in La 3 Ni 2 O 7. Temperature-dependent relaxation time diverges near the density-wave transition temperature of La 4 Ni 3 O 10 , while it is inversely proportional to the temperature in La 3 Ni 2 O 7 above ∼150 K, suggesting a non-Fermi liquid behavior of La 3 Ni 2 O 7. Moreover, we estimate the electron–phonon coupling constants to be 0.05–0.07 and 0.12–0.16 for La 3 Ni 2 O 7 and La 4 Ni 3 O 10 , respectively, suggesting a relatively minor role of electron–phonon coupling in the electronic properties of La n +1 Ni n O 3 n +1 at ambient pressure. The relevant microscopic interaction and dynamic information are essential for further studying the interplay between superconductivity and density-wave transitions in nickelate superconductors. [ABSTRACT FROM AUTHOR]

Structural regulation of crystal structures to achieve specific structural architectures and/or desired functionalities is one of the main focuses in the field of molecular magnetism. The reaction of a trigonal tetradentate ligand, [TpFeIII(CN)3]− bridging unit and cobalt metal centres by the altering change of chemical stoichiometry afforded three different structures [{TpFe(CN)3}2Co(PyPz3)]·4MeOH·5H2O (1), [{TpFe(CN)3}Co(PyPz3)]2(ClO4)2·2MeCN·2H2O (2) and {(Tp)Fe(CN)3Co(PyPz3)}n(BF4)n·2nMeOH (3) (PyPz3 = 2-(di(1H-pyrazol-1-yl)methyl)-6-(1H-pyrazol-1-yl)pyridine and [TpFeIII(CN)3]− = tri(pyrazolyl)boratetricyanoiron(III)). Detailed structural studies reveal a gradual transformation among the complexes, from a trinuclear structure in 1, to a tetranuclear geometry in 2, and finally to a one-dimensional chain in 3. Magnetic susceptibility measurements revealed that all three complexes exhibit ferromagnetic interactions between the cyanide bridged FeIII and CoII centres, with exchange coupling constants of +7.89, +4.37, and +5.92 cm−1, respectively. Our result demonstrates an effective strategy for targeted assembly of architectures by introducing coordinatively unsaturated ligands, complemented by the cyanide-bridged linkers [TpRFeIII(CN)3]−. [ABSTRACT FROM AUTHOR]

This paper discusses hyperconjugative stereoelectronic effects in borazines. A series of alkyl-substituted borazines were synthesized and analysed by NMR spectroscopy and X-ray diffraction. Supported by NBO analyses, the significant decreases in 1JCH coupling constant for the CH groups adjacent to the boron atoms are consistent with the presence of and interactions. These interactions lower the electrophilicity of boron atoms, enhancing moisture stability and establishing these molecules as valuable scaffolds in synthetic chemistry and materials science. [ABSTRACT FROM AUTHOR]

In this paper, the vacuum energy density and generation of topological mass are investigated for a system of a real and complex scalar fields interacting with each other. In addition to that, it is also included the quartic self-interaction for each one of the fields. The condition imposed on the real field is the periodic condition, while the complex field obey a quasi-periodic condition. The system is placed in a scenario where the CPT-even aether-type Lorentz symmetry violation takes place. We allow that the Lorentz violation affects the fields with different intensities. The vacuum energy density, its loop correction, and the topological mass are evaluated analytically. It is also discussed the possibility of different vacuum states and their corresponding stability requirements, which depends on the conditions imposed on the fields, the interaction coupling constants and also the Lorentz violation parameters. The formalism used here to perform this investigation is the effective potential one, which is written as a loop expansion via path integral in quantum field theory. [ABSTRACT FROM AUTHOR]

The constant current followed by constant voltage (CC-CV) charging method is commonly employed for battery charging, effectively extending battery life and reducing charging time. However, as charging progresses, the battery's internal resistance increases, complicating the charging circuit. This paper designs a wireless power transfer system utilizing an LCL coupling network for battery charging. The system employs frequency modulation (FM) to manage its CC and CV output characteristics at two fixed frequency points. The influence of the LCL coupling network parameters on system output characteristics was investigated using MATLAB. A simulation model was developed in the PSIM environment to validate the CC and CV output characteristics. The simulation results show that the system has load-independent constant-current and constant-voltage characteristics at two different frequency points. In order to verify the theoretical analysis, an experimental platform was also established. Experimental results demonstrate that the proposed system operates effectively in CC mode, maintaining constant output current across various loads, while in CV mode, it effectively regulates output voltage for different loads. The designed frequency modulation controller ensures a rapid response to sudden changes in load resistance, regardless of operating in CC or CV modes. [ABSTRACT FROM AUTHOR]

In this work, we investigate some extensions of the Kiselev black hole solutions in the context of f(핋,풯) gravity. By mapping the components of the Kiselev energy–momentum tensor into the anisotropic energy–momentum tensor and assuming a particular form of f(핋,풯), we obtain exact solutions for the field equations in this theory that carries dependence on the coupling constant and on the parameter of the equation of state of the fluid. We show that in this scenario of modified gravity some new structure is added to the geometry of spacetime as compared to the Kiselev black hole. We analyze the energy conditions, mass, horizons and the Hawking temperature considering particular values for the parameter of the equation of state. [ABSTRACT FROM AUTHOR]

Endohedral metallofullerenes (EMFs) are constructed by fullerene cages encapsulating various metal atoms or metal clusters, which usually exhibit some motion. However, due to the fact that the elusive endohedral dynamics are related to many factors, it remains a challenge to image the motion of internal species. Recently, the electron spin was found to be a sensitive probe to detect the motion of internal species in EMFs. Moreover, this technique can be widely applied for many metallofullerenes, i.e., for paramagnetic EMFs, the unpaired electron spin is a natural probe for the endohedral dynamics, and for diamagnetic EMFs, an electron can be introduced to produce spin-active EMF molecules. Based on the analysis of hyperfine coupling constants (hfcc), g-factors, and line patterns of the ESR spectra of EMFs, the spin centers and endohedral dynamics can be deduced. It has been revealed that the spin probes can provide unexpected information about the dynamics of the internal clusters in EMFs. Through changing the temperature, exohedral modification of the EMF, and supramolecular assembly, the motion of the internal species in EMFs can be manipulated, as clearly reflected by the spin probe. These studies revealed that the spin in EMFs exhibits promising applications in quantum sensing and molecular machine technology. In this review, we will address the use of the spin probe in EMFs and attempt to understand the effects in the detection of the endohedral dynamics. [ABSTRACT FROM AUTHOR]

The discovery of ~80 K superconductivity in nickelate La3Ni2O7 under pressure has ignited intense interest. Here, we present a comprehensive first-principles study of the electron-phonon (e-ph) coupling in La3Ni2O7 and its implications on the observed superconductivity. Our results conclude that the e-ph coupling is too weak (with a coupling constant λ ≲ 0.5) to account for the high Tc, albeit interesting many-electron correlation effects exist. While Coulomb interactions (via GW self-energy and Hubbard U) enhance the e-ph coupling strength, electron doping (oxygen vacancies) introduces no major changes. Additionally, different structural phases display varying characteristics near the Fermi level, but do not alter the conclusion. The e-ph coupling landscape of La3Ni2O7 is intrinsically different from that of infinite-layer nickelates. These findings suggest that a phonon-mediated mechanism is unlikely to be responsible for the observed superconductivity in La3Ni2O7, pointing instead to an unconventional nature. [ABSTRACT FROM AUTHOR]

In this paper, we study the dynamical stability analysis by considering the torsion field ϕ which is proportional to the Hubble parameter and barotropic equation-of-state parameter in the framework of the homogenous and isotropic FLRW metric with non-zero torsion in the scenario of dark matter and dark energy interacting terms. We discuss the stability of the critical points corresponding to the eigenvalues in the presence of dust and radiation at quintessence, Λ CDM and phantom regimes by utilizing the different linear and nonlinear interaction models which depend on the energy density. As a result, we observe that the first linear model shows the stable behavior throughout the universe for dust and radiation phase. The other linear and nonlinear models show the stable critical points, computing with the eigenvalues at phantom and Λ CDM era with the best fit value of interaction strength and coupling constant for dust and radiation. [ABSTRACT FROM AUTHOR]

The quantitative solution conformations of 2‐(hydroxymethyl)‐tetrahydropyran, α‐methyl‐d‐mannopyranoside, and 6‐[α‐d‐mannopyranosyl]‐d‐mannopyranose (mannobiose) are described. Parametrized Karplus equations for redundant spin pairs across the terminal ω‐torsion and the glycosidic ω‐torsion for mannobiose are developed, including ω/θ‐hypersurfaces for the terminal hydroxymethylene group. Experimental NMR data, algorithmic spectral simulation (clustered Hamiltonian method), molecular dynamics (MD) simulations (GLYCAM06), energy minimizations by DFT, and adjusted torsion angle populations weighted over the Karplus‐type equations are used. We demonstrate that spectral simulation is a powerful tool in the refinement of initial J values obtained from static GAIO DFT calculations. We also show that only as few as one of multiple redundant torsions can be diagnostic for conformational analysis of the disaccharide. [ABSTRACT FROM AUTHOR]

In this paper, we study an effective field theory (EFT) for a singlet scalar extension of the standard model (SM). The tree- and one-loop level effective actions are derived by integrating out the heavy singlet scalar in the Lagrangian for the UV theory and by applying to the functional method, respectively. In the UV model, the light scalar field identified with the SM Higgs is assumed to be massless in the symmetric phase. When the heavy singlet scalar acquires a vacuum expectation value, the Z2 symmetry is broken and a mass term of the light scalar is induced. In light of EFT we derive, the electroweak vacuum resulting in 126GeV Higgs mass can be attained when the induced squared-mass term of the light scalar in the scalar potential becomes negative. This condition can occur when the constant of the scalar coupling between the two different scalars is allowed to be negative. We investigate how the EFT can be constrained by theory and experiments. We also examine whether or not electroweak phase transition (EWPT) in this scenario can be a first order. Some numerical results leading to the first-order EWPT while satisfying the constraints studied are presented. [ABSTRACT FROM AUTHOR]

This paper proposes an elastic topological resonator derived from the Kekulé tight-binding model, which enables the quantum spin Hall effect (QSHE). Band inversion in the spin system is realized through fine-tuning the intracellular coupling constants. With full-wave simulations, the topological interface configurations demonstrate the robust spin-locked edge state transport characteristic, featuring excellent fidelity via defects and anti-direct transmission. Then, a hexagonal resonator is located beside the straight waveguide to achieve multiple effective coupling directed by the edge state. The effect of the distance between the straight waveguide and the hexagonal part is further analyzed on the number of the resonant mode. Based on the functionally graded design concept, the topological resonance rainbow is also proposed to spatially separate distinct frequency components in accordance with projected band branches, to realize the progressive propagation of Lamb waves along the resonator route. Our work provides a novel mechanism for manipulating elastic waves with topological edge states, which is anticipated to serve as a foundation for creating programmable sensors and multifunctional testing equipment. [ABSTRACT FROM AUTHOR]

The μ‐phenoxido‐bridged dinuclear copper(II) complex, [Cu2(L1)2(dmso)(MeOH)] (1), has been synthesized using N′‐(4‐(diethylamino)‐2‐hydroxybenzylidene)‐1‐naphthohydrazide (H2L1) as ligand. The structural analysis of 1 reveals that the coordination geometry at the copper ions is best described as a square pyramidal with a Cu⋅⋅⋅Cu distance in the dinuclear complex of 303 pm which is supported by hydrogen bonding between the two apical oxygen donor ligands (O⋅⋅⋅O 277 pm). Magnetic studies indicate that 1 exhibits a strong antiferromagnetic interaction between the two copper(II) ions with a coupling constant of J=−450 cm−1 (H^=-JS^1S^2 ${\widehat{{\rm H}}=-J{\widehat{{\rm S}}}_{1}{\widehat{{\rm S}}}_{2}}$). The magnetic exchange is transmitted through the central [Cu2(OR)2]2+ core, a fragment for which different magneto‐structural correlations have been reported depending on the substituent at the bridging oxygen atom. However, the properties of complex 1 cannot be explained by any of the established correlations. Nevertheless, complex 1, together with the series of compounds based on an acylhydrazone ligand framework reported so far, shows a magneto‐structural correlation as a function of the Cu−O−Cu bridging angle that significantly differs from all previously reported. [ABSTRACT FROM AUTHOR]

Achieving room-temperature superconductivity under ambient conditions is one of the most important goals in solid-state physics and material science. Recent discoveries of high-Tc superconductivity in binary hydrides H3S and LaH10 at high pressures have focused the search for room-temperature superconductors on dense hydrides with conventional phonon-mediated pairing mechanisms. In this study, we predict a novel family of superconducting ternary hydrides under moderate compression, XC2H8 (X = Ga, In, Tl, Sn, Pb, Sb, Bi, Te, Po). Unlike H3S and LaH10, these new materials are stable at just around 20 GPa. Among the analyzed compounds, SbC2H8 exhibits the highest critical temperature of 73 K at a pressure of 100 GPa, which is attributed to its energetically favorable high-symmetry crystal structure ( F m 3 ¯ m ), high density of states at the Fermi level (1.27 states/eV) and strong electron–phonon coupling constant (1.02). We expect that our findings provide crucial insights into achieving high-temperature superconductivity at moderate pressures and accelerate the progress of experimental research. [ABSTRACT FROM AUTHOR]

ABSTRACT Sr2YRuO6 is a material that provides an ideal platform for studying magnetic frustration in three‐dimensional geometries. Herein, we combine Raman spectroscopy and density functional theory calculations to establish connections between the lattice dynamics and magnetic states in Sr2YRuO6 single crystals. The x‐ray diffraction profiles reveal that Sr2YRuO6 possesses an ordered double‐perovskite structure with distorted monoclinic symmetry. Three magnetic phase transitions are observed and linked to the presence of weak ferromagnetism at 135 K and short‐ and long‐range antiferromagnetic orderings at 32 and 26 K. The oxygen‐octahedron antistretching and stretching modes, observed at 570 and 766 cm−1, exhibit anomalies near the magnetic phase transition temperatures, indicating an intriguing interplay between the lattice and spin degrees of freedom. Their spin–phonon coupling constants of 0.7 cm−1 reflect the weak spin–lattice interactions in Sr2YRuO6. [ABSTRACT FROM AUTHOR]

The study of phonon coupling in doped semiconductors via electrical transport measurements is challenging due to unwanted temperature-induced effects such as dopant ionization and parallel conduction. Here, we study phonon scattering in 2D electrons and holes in the 1.6 – 92.5 K range without the use of extrinsic doping, where both acoustic and longitudinal optic (LO) phonons come into effect. We use undoped GaAs/ Al x Ga 1 − x As heterostructures and examine the temperature dependence of the sample resistivity, extracting phonon coupling constants and the LO activation energy. Our results are consistent with results obtained through approaches other than transport measurements and highlight the benefit of this approach for studying electron–phonon and hole–phonon coupling. [ABSTRACT FROM AUTHOR]

In this paper, we consider the group formed by finite renormalizations as an infinite-dimensional Lie group. It is demonstrated that for the finite renormalization of the gauge coupling constant, its generators L ̂ n with n ≥ 1 satisfy the commutation relations of the Witt algebra and, therefore, form its subalgebra. The commutation relations are also written for the more general case when finite renormalizations are made for both the coupling constant and matter fields. We also construct the generator of the Abelian subgroup corresponding to the changes of the renormalization scale. The explicit expressions for the renormalization group generators are written in the case when they act on the β -function and the anomalous dimension. It is explained how the finite changes of these functions under the finite renormalizations can be obtained with the help of the exponential map. [ABSTRACT FROM AUTHOR]

We determine the closed-form solution of a three-dimensional stationary Schrödinger equation for an angular-dependent potential in spherical coordinates within the Dunkl formalism. Furthermore, we calculate the change of the system's total energy with respect to coupling constants in the potential by means of the Hellman–Feynman theorem. [ABSTRACT FROM AUTHOR]

A nonuniform condensate is usually described by the Gross–Pitaevskii (GP) equation, which is derived with the help of the c-number ansatz Ψ ^ (r , t) = Ψ (r , t) . Proceeding from a more accurate operator ansatz Ψ ^ (r , t) = a ^ 0 Ψ (r , t) / N , where N is the number of Bose particles, we find the equation i ℏ ∂ Ψ (r , t) ∂ t = − ℏ 2 2 m ∂ 2 Ψ (r , t) ∂ r 2 + (1 − 1 N) 2 c Ψ (r , t) | Ψ (r , t) | 2 , which we call the GP N equation. It differs from the GP equation by the factor (1 − 1 / N) . We compare the accuracy of the GP and GP N equations by analysing the ground state of a one-dimensional system of point bosons with repulsive interaction (c > 0) and zero boundary conditions. Both equations are solved numerically, and the system energy E and the particle density profile ρ (x) are determined for the mean particle density ρ ¯ = 1 , different values of N and of the coupling constant γ = c / ρ ¯ . The solutions are compared with the exact ones obtained by the Bethe ansatz. The results show that the GP and GP N equations equally well describe the many-particle system ( N ≳ 100 ) being in the weak coupling regime ( N − 2 ≪ γ ≲ 0.1 ). But for the few-boson system ( N ≲ 10 ) with γ ≲ N − 2 the solutions of the GP N equation are in much better agreement with the exact ones. Thus, the multiplier (1 − 1 / N) allows one to describe few-boson systems with high accuracy. This means that it is reasonable to extend the notion of Bose–Einstein condensation to few-particle systems. [ABSTRACT FROM AUTHOR]

In this paper, we are concerned with the following Schrödinger system { − Δ u + P (x) u = μ 1 u 3 + β 1 u v 2 + β 2 u w 2 , x ∈ R 3 , − Δ v + Q (x) v = μ 2 v 3 + β 1 v u 2 + β 3 v w 2 , x ∈ R 3 , − Δ w + λ w = μ 3 w 3 + β 2 w u 2 + β 3 w v 2 , x ∈ R 3 , where λ > 0 is a positive constant, P (x) , Q (x) are continuous positive radial potentials, μ i (i = 1 , 2 , 3) > 0 and β i (i = 1 , 2 , 3) ∈ R are coupling constants. We mainly investigate the effect of the potentials and the nonlinear coupling on the structure of solutions. Applying the Lyapunov-Schmidt reduction method, we prove the existence of infinitely many positive solutions and sign-changing solutions to the system whose energy can be arbitrarily large. Specifically, we obtain solutions with some of the components synchronized between them while segregated with the rest of the components. Moreover, we also show the existence of another solutions with all components segregated, one of which concentrates at the origin. Our results present vector solutions to the system with different characters. To our knowledge, it is the first time to study systems with three equations involving mixed potentials. [ABSTRACT FROM AUTHOR]

We measured the μ + SR Knight shift in the hole-doped organic metal κ -(ET) 4 Hg 3 - δ Cl 8 , δ =22%, and re-analyzed temperature dependence of μ + SR Knight shift of the isostructural compound κ -(ET) 4 Hg 3 - δ Br 8 , δ =11%. The former underwent insulating and the latter has superconducting ground state. By lowering temperature the Knight shift gradually increased and was almost unchanged for κ -HgCl and κ -HgBr metals, respectively. We found a prominent deviation from linearity in the K (χ) plot of κ -HgCl below 100 K whereas the result of reanalysis of κ -HgBr shows there is almost no linearity of the K (χ) plot, although the absolute value of the μ + Knight shift K is comparable with that of κ -HgCl at low-temperature. The hyperfine coupling constant of κ -HgCl was estimated as A hf (κ -HgCl) = 282 Oe/ μ B . This value is comparable with our calculation assuming a point dipole between muon site, determined by the electronic potential calculation using density functional theory, and the localized spin at the Cl site. In consideration of both samples being in the vicinity of same quantum criticality, the muon Knight shift is more sensitive to the insulating sample with enhanced antiferromagnetic fluctuations. We discuss the relation between enhanced antiferromagnetic spin fluctuations, Non-Fermi liquidity, and superconductivity in these systems. [ABSTRACT FROM AUTHOR]

In order to undestand the muon experiments in hemoglobin, we perform density functional theory (DFT) calculations to estimate the muonium (Mu) behavior in four derivatives (deoxyhemoglobin, oxyhemoglobin, carboxyhemoglobin and methemoglobin) of hemoglobin. The DFT calculations using B3LYP/6-31G level of theory shows the stopping site of Mu is found near the unsaturated N of imidazole ring of histidine amio acid connected to Fe of heme group. The estimated hyperfine coupling terms will be helpful to support the muon experiment in these derivatives. [ABSTRACT FROM AUTHOR]

The 14N nuclear quadrupole resonance (NQR) spectrum of glybenclamide has been recorded using cross relaxation Double Resonance. Glybenclamide, also known as glibenclamide or glyburide, belongs to the class of sulfonylurea drugs. It is used as antidiabetic medication solely, or combined with biguanides such as metformin, to treat Type 2 Diabetes Mellitus. Glybenclamide has three distinct nitrogen atoms, two belong to the sulfonylurea group and the third is an amide nitrogen. The 14N NQR experimental quadrupole coupling constants (χ) and asymmetry parameters (η) of glybenclamide have been compared to its calculated ab-initio and DFT values and the orientation of the principal EFG axes for each nitrogen atom has been assigned. The nitrogen atom adjacent to the sulfonyl group has the largest calculated χ, and by extension, the largest qzz EFG component. The experimental η and χ values for the amide nitrogen atom indicate the presence of intramolecular hydrogen bonding in the molecule. 14N NQR Spectrum of Glybenclamide (aka Glibenclamide) [ABSTRACT FROM AUTHOR]

The 14N nuclear quadrupole resonance (NQR) spectra of two common benzodiazepines, Diazepam and Lorazepam, have been recorded using cross relaxation double resonance. Benzodiazepines are characterized by a fused diazepine and benzene ring and act as central nervous system depressants or tranquilizers. Each compound has two distinct nitrogen atoms in their molecular structure. Both nitrogen atoms of diazepam have similar asymmetry parameters. However, the imine nitrogen of diazepam has a slightly higher quadrupole coupling constant (χ) than its tertiary amide nitrogen. The 14N NQR signals of lorazepam suggests that there is more than one form present in the solid. The imine nitrogen shows similar frequencies and NQR parameters to that of diazepam. However, the frequencies assigned to the secondary amide nitrogen result in a lower χ and a relatively higher asymmetry parameter (η) than the amide nitrogen of diazepam. This has been attributed to hydrogen bonding of the amide proton in lorazepam. Ab-initio and DFT calculations have been performed to support the assignments. [ABSTRACT FROM AUTHOR]

We present the results of 27 Al-nuclear magnetic resonance (NMR) studies of Si-substituted PrTi 2 Al 20 in order to clarify the magnetic and electronic properties at low temperatures and the change by Si substitution for Al from a microscopic point of view. From the analyses of the Knight shift, the hyperfine coupling constants on 27 Al in PrTi 2 (Si 0.1 Al 0.9 ) 20 are slightly larger than those of PrTi 2 Al 20 . The nuclear spin-lattice relaxation rate 1 / T 1 does not exhibit any anomaly around 2.0 K, in contrast to the results associated with the quadrupolar ordering in PrTi 2 Al 20 . The analysis of 1 / T 1 at high temperatures reveals that the c – f hybridization may be reduced by Si substitution for Al. [ABSTRACT FROM AUTHOR]

We study two harmonic oscillators with high quality factors, driven by equilibrium and off equilibrium thermal noise, the latter mimicked by establishing a temperature gradient. The two oscillators are coupled via a third reciprocal harmonic interaction. We deepen the case of a weak coupling between the two oscillators, and show the emergence of a "spike" in the displacement variance of the colder oscillator, when the respective elastic constants approach each other. Away from the peak, the displacement variance of each oscillator only reflects the value of the local temperature. We name this phenomenon the variance resonance, or alternatively covariance resonance, in the sense that it comes about as one element of the covariance matrix describing both oscillators. In fact, all of the elements of the covariance matrix show some distinctive behavior. The oscillator at the lower temperature, therefore, oscillates as if driven by a higher temperature, resonating with the other one. By converse, the variance of the hotter oscillator develops a deep dent, or depression, around the same region. We could not reproduce this behavior if either the coupling constant is not small compared to those of the two oscillators, or if the quality factors are not large enough. In fact, in such instances the system tends to resemble one which is in equilibrium at the average temperature, regardless of the relative strengths of the elastic constants of the two oscillators. Our results could have various applications including for example precision measurement systems, when not all parts of the apparatuses are at the same temperature. [ABSTRACT FROM AUTHOR]

Conventional spectral probes of quantum chaos require eigenvalues, and sometimes, eigenvectors of the quantum Hamiltonian. This involves computationally expensive diagonalization procedures. We test whether an unsupervised neural network can detect quantum chaos directly from the Hamiltonian matrix. We use a single-body Hamiltonian with an underlying random graph structure and random coupling constants, with a parameter that determines the randomness of the graph. The spectral analysis shows that increasing the amount of randomness in the underlying graph results in a transition from integrable spectral statistics to chaotic ones. We show that the same transition can be detected via unsupervised neural networks, or more specifically, self-organizing maps by feeding the Hamiltonian matrix directly into the neural network, without any diagonalization procedure. [ABSTRACT FROM AUTHOR]

In this work, a master–slave system composed by a pair of damped Duffing oscillators with variable coefficients and nonlinear coupling is investigated. An integral of motion for the system is obtained using a symmetry transformation and Noether's theorem. Some numerical examples are presented for different cases of damping and oscillation frequency, for a varying coupling constant. The system dynamics is studied by means of space-time surfaces, time series and phase portraits. For a constant oscillation frequency, the slave presents envelopes that tend to become chaotic as the coupling constant increases. Meanwhile, as the frequency increases with time, the slave has higher amplitudes and speeds than the master oscillator. [ABSTRACT FROM AUTHOR]

A novel 2-(2,3,4-trimethoxyphenyl)-1H-phenanthro[9,10-d]imidazole crystal has been reported and characterized by FT-IR, 1H NMR, and 13C NMR spectral techniques. Single-crystal XRD studies reveal that the compound crystallizes into orthorhombic crystal system with Pbcn space group, and crystallographic data have been deposited in the Cambridge crystallographic data centre with CCDC number: 2244532. Various computational analyses such as hydrogen bond analysis, molecular electrostatic potential analysis, natural population analysis, Hirshfeld surface, and Frontier molecular orbital analysis were performed to elucidate the structure of the crystal. The calculation of reorganization energy and coupling constant using DFT methods reveals that the compound could be investigated as a hole transport material. [ABSTRACT FROM AUTHOR]

The title compound was characterised for the first time by 13C NMR, including the determination of CH coupling constants, and its X-ray structure was determined, showing double ribbons of molecules in the crystal held together by weak CH to O=C hydrogen bonds. [ABSTRACT FROM AUTHOR]

The angular dependence of the indirect short‐range spin‐spin coupling constants (SSCC), the geminal J(C3,C1′)$$ J\left({C}_3,{C}_{1^{\prime }}\right) $$, J(O1,O)$$ J\left({O}_1,O\right) $$, and J(O,C1′)$$ J\left(O,{C}_{1^{\prime }}\right) $$ in A‐type dimeric proanthocyanidin, was investigated using density functional theory. We studied the rotation of ring B around the C2–C1′$$ {C}_2\hbox{--} {C}_{1^{\prime }} $$ bond. Therefore, we calculated hyperconjugative charge transfers and bond polarizations within the natural bond orbital (NBO) approach, performing a topological study based on Bader's theory, AIM (atoms in molecules), and analyzing the angular dependence of AIM/NBO parameters. The results describe a relationship between the geminal coupling that changes with angular variation and NBO charge transfers to the bonds involved in the coupling pathways that can explain the behavior of the former property. Based on AIM/NBO data, inductive and mesomeric effects were described and quantified, showing a clear correlation with the stabilization of the structure, demonstrating a resonance‐assisted inductive effect. We also set out strong hyperconjugative interactions (anomeric effect) involving nonbonding electron pairs of oxygen atoms. This analysis of coupling constants supports previous models by other authors and shows the application in this particular case. Moreover, the SSCCs studied herein are used for identifying stable structures and conformational search analysis of flavonoids. Finally, our results show the relationship between SSCCs and the structure stabilization and charge delocalization effects. [ABSTRACT FROM AUTHOR]

We consider the standard first passage percolation model on Z d with a distribution G taking two values 0 < a < b . We study the maximal flow through the cylinder [ 0 , n ] d - 1 × [ 0 , h n ] between its top and bottom as well as its associated minimal surface(s). We prove that the variance of the maximal flow is superconcentrated, i.e. in O (n d - 1 log n) , for h ≥ h 0 (for a large enough constant h 0 = h 0 (a , b) ). Equivalently, we obtain that the ground state energy of a disordered Ising ferromagnet in a cylinder [ 0 , n ] d - 1 × [ 0 , h n ] is superconcentrated when opposite boundary conditions are applied at the top and bottom faces and for a large enough constant h ≥ h 0 (which depends on the law of the coupling constants). Our proof is inspired by the proof of Benjamini–Kalai–Schramm (Ann Probab 31:1970–1978, 2003). Yet, one major difficulty in this setting is to control the influence of the edges since the averaging trick used in Benjamini et al. (Ann Probab 31:1970–1978, 2003) fails for surfaces. Of independent interest, we prove that minimal surfaces (in the present discrete setting) cannot have long thin chimneys. [ABSTRACT FROM AUTHOR]

We study the dependence of the beta-function on the running coupling constant in holographic models supported by the Einstein–dilaton–Maxwell action for light and heavy quarks. The dilaton defines the running coupling of the models. Its dependence on boundary conditions leads to the running coupling dependence on them. However, the behavior of the -function as a function of the running coupling does not depend significantly on the boundary condition. The corresponding -functions are negative and monotonically decreasing functions, and have jumps at first-order phase transitions for both light and heavy quarks. In addition, we compare our holographic results for the -function as a function of the running coupling with perturbative results obtained within -loop calculations. [ABSTRACT FROM AUTHOR]

Poisson's ratio in chiral isotropic elastic solids can be larger or smaller than the classical thermodynamic bounds. The effect of Cosserat coupling constant k is studied. Analysis shows that solids with weak coupling exhibit Poisson's ratio anomalies for larger specimen sizes than corresponding solids with strong coupling. Experiments on a quasi‐isotropic composite with chiral inclusions show Poisson's ratio greater than 0.5. [ABSTRACT FROM AUTHOR]

In this paper, we explore a stationary BTZ space-time within the framework of modified gravity theory, specifically focusing on Ricci-inverse gravity. It is important to clarify that "Ricci-inverse" refers to the inverse of the Ricci tensor, not the Ricci scalar. We consider a general class of this gravity theory, where the function f is defined by f (R , A , A μ ν A μ ν) , with R and A representing the Ricci and anti-curvature scalars, respectively and A μ ν is the anti-curvature tensor. We demonstrate that stationary BTZ space-time is a valid solution in this gravity theory, wherein the cosmological constant undergoes modifications due to the coupling constants. Moreover, we study another modified gravity theory known as f (R) -gravity and analyze the stationary BTZ space-time. Subsequently, we fully integrate the geodesic equations for BTZ space-time constructed within the Ricci-Inverse gravity, expressing the solutions in terms of elementary functions and compared with the GR result. We classify different types of geodesics, including null and time-like geodesics, under three conditions: (i) nonzero mass and angular momentum, M ≠ 0 , J ≠ 0 , (ii) massless BTZ space-time, M = 0 and J = 0 , and (iii) M = - 1 , J = 0 , that is A d S 3 -type, and analyze the results in modified gravity theories and compare with the general relativity case. [ABSTRACT FROM AUTHOR]

We use the bond mean field theory, which is based on the Jordan–Wigner fermionization, to investigate the quantum critical behavior of a system composed of two-coupled Heisenberg Spin- 1 / 2 two-leg ladders in the presence of an applied magnetic field. By examining the dependence of the ground state on the magnetic field for different coupling constants, we investigate the field-induced quantum criticality. The magnetization exhibits distinct plateaus: a zero magnetization plateau for fields below a threshold value of the field h c 1 and a saturation plateau for fields exceeding a second critical value h c 2 . The spin bond parameters are calculated and found to show a critical behavior at h c 2 . [ABSTRACT FROM AUTHOR]

In this paper, a pulsed laser is applied to realize these complicated thermal cycles experimentally, coupling with the constant mechanical loading with the self-designed sample holder. A numerical simulation model is proposed to calculate the temperature and stress under thermal cycles of variable amplitude coupled with mechanical loading. The findings indicate a strong correlation between the measured temperature curve and the simulated results under various loading parameters. It is observed that the calculated depth of thermal–structural interaction for low-cycle conditions exceeds that of high-cycle conditions. In addition, the mechanism of crack evolution under thermal cycles of variable amplitude coupled with mechanical loading is discussed. This paper offers extensive experimental and numerical perspectives on the damage process occurring under thermal cycles of varying amplitudes combined with mechanical loading, highlighting its substantial engineering importance for conducting failure analyses and optimizing the design of hot-end components. [ABSTRACT FROM AUTHOR]

Is the 1JC−H coupling constant for protonated carbene a relevant measure of its σ‐donation ability? This paper addresses this question by comparing calculated 1JC−H values with various experimental and theoretical approaches across a broad spectrum of carbene compounds. We examined Arduengo‐type NHCs based on the 2‐imidazolylidene scaffold and many other derivatives with modified frameworks, including carbenes with extended, saturated, or conjugated rings, reduced heteroatom stabilization, alternative heteroatoms, permanently charged carbenes, acyclic carbenes, amidocarbenes, and cyclic amino(alkyl/aryl) carbenes, carbodicarbenes and carbodiphosphoranes. Our findings reveal a nuanced relationship between different parameters associated with σ‐interaction, such as 1JC−H, Huynh electronic parameter (HEP), σ‐donation from ETS‐NOCV, and lone pair energy. Notably, the best correlation was observed between 1JC−H and the ETS‐NOCV method, particularly for mono‐ and diaminocarbenes, highlighting the utility of 1JC−H in comparing σ‐donation among structurally similar carbene types. However, the use of 1JC−H as a universal measure across all carbene classes appears limited, especially when considering carbenes with significantly different structural frameworks. While HEP is less effective for carbenes with diverse structural backbones, our study suggests that 1JC−H has potential across a broader range of systems. Additionally, the analysis demonstrates that lone pair energy reflects basicity rather than σ‐donor ability. [ABSTRACT FROM AUTHOR]

The elastic cross-section is calculated for the elements 12C, 40Ca and 4He at high energies using the radial Klein–Gordon equation. These calculations were made for the case of pions using the Yukawa potential. To this end, the coupling constant of the Yukawa potential for the elements 12C, 40Ca and 4He was calculated first by fitting the numerical solutions to the experimental data. Our results are in agreement with the experimental data at low angular distribution. Finally, we calculate the bounds for the parameter of the model. [ABSTRACT FROM AUTHOR]

The influence of tachyonic instability on the Schwinger effect is investigated by axial coupling in the natural single‐field inflation model when strong back‐reaction exists in two parts. First, the Schwinger effect is considered when the conformal invariance of Maxwell action should be broken by axial coupling I(ϕ)FμνF∼μν$ I(\phi)F_{\mu \nu }\tilde{F}^{\mu \nu }$ with the inflaton field by identifying the standard horizon scale k=aH$ k=aH$ at the very beginning of inflation for additional boundary term and use several values of coupling constant χ1$ \chi _{1}$ and estimate electric and magnetic energy densities and energy density of produced charged particles due to the Schwinger effect. It has been found that for both coupling functions the energy density of the produced charged particles due to the Schwinger effect is so high and spoils inflaton field. In fact the strong coupling or back‐reaction occurs because the energy density of produced charged particles is exceeding of inflaton field. Two coupling functions are used to break conformal invariance of maxwell action. The simplest coupling function Iϕ=χ1ϕMp$ I\left(\phi \right)=\chi _{1}\frac{\phi }{M_{p}}$ and a curvature based coupling function Iϕ=12χ1e23ϕMp13Mp24Vϕ+23MpdVdϕ$ I\left(\phi \right)= 12\chi _{1}e^{\left(\sqrt {\frac{2}{3}}\frac{\phi }{M_{p}}\right)}\left[\frac{1}{3M_{p}^{2}}\left(4V\left(\phi \right)\right)+\frac{\sqrt {2}}{\sqrt {3}M_{p}}\left(\frac{dV}{d\phi }\right)\right]$ where Vϕ$V\left(\phi \right)$ is the potential of natural inflation. In second part, in oder to avoid strong back‐reaction problem, the horizon scale kH=aH|ζ|,ζ=I′ϕϕ̇H$ k_{H}=aH|\zeta |, \zeta =\frac{{I}^{\prime }\left(\phi \right)\dot{\phi }}{H}$ is identified in which a given Fourier begins to become tachyonically unstable.The influence of this scale is reducing the value of coupling constant χ1$ \chi _{1}$ and weakening the back‐reaction problem but in both cases strong coupling or strong back‐reaction exists and the Schwinger effect is impossible. Therefore, the Schwinger effect in this model is not possible and spoils inflation. Instantly, the Schwinger effect produces very high energy density of charged particles which causes back‐reaction problem and spoils inflaton field. It has been stressed that due to existence of strong back‐reaction in two cases the energy density of the produced charged particles due to the Schwinger effect spoils inflation. The influence of tachyonic instability in this model is quiet different from our published work in Kamarpour. In Kamarpour, this effect appears by vanishing of electromagnetic energy density and the energy density of charged particles at the very beginning of inflation. [ABSTRACT FROM AUTHOR]