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Applying classical molecular dynamics simulations, we report the effects of length (λ) and orientation (θ) of a line-defect on strength and toughness in defective 2D hexagonal boron nitride. Results reveal the existence of a "transition angle," θ t = 2.47 ° , at which both toughness and strength are insensitive to the finite length of the defect in an infinite domain. For θ < θ t , both toughness and strength increase with an increase in defect-length; whereas, for θ > --> θ t , they show the opposite behavior. Examination of the stress-fields shows that θ -dependent variation in stress-localization at the edges of the line-defect and symmetry-breaking of the stress-fields with respect to the defect-axis govern the disparate θ -dependent behavior. For θ < θ t , the intensity of elastic fields at the edges of the line-defect is substantially weakened by the elastic interactions originating from the atoms on the sides of the line-defect. For θ > --> θ t , the stress-intensity at the edges is strongly localized at the opposite sides of the line-defect. The stress-intensity increases asymptotically with the increasing defect-length and reduces the strength and toughness of the defective lattice. The stress-localization, however, saturates at a "saturation angle" of around 60 ° for strength and 30 ° for toughness. Additionally, there exists a critical defect-length λ c = 60 Å, below which there is a strong θ -dependent variation in elastic interactions between the edges, affecting strength and toughness substantially. For λ > --> λ c , the elastic interactions saturate and make both strength and toughness insensitive to the change in the length of the defect. [ABSTRACT FROM AUTHOR]

Abstract: Plasmonic nanostructures have demonstrated a remarkable ability to control light in ways never observed in nature, as the optical response is closely linked to their flexible geometric design. Due to lack of mirror symmetry, chiral nanostructures allow twisted electric field “hotspots” to form at the material surface. These hotspots depend strongly on the optical wavelength and nanostructure geometry. Understanding the properties of these chiral hotspots is crucial for their applications; for instance, in enhancing the optical interactions with chiral molecules. Here, the results of an elegant experiment are presented: by designing 35 intermediate geometries, the structure is “enantiomorphed” from one handedness to the other, passing through an achiral geometry. Nonlinear multiphoton microscopy is used to demonstrate a new kind of double‐bisignate circular dichroism due to enantiomorphing, rather than wavelength change. From group theory, a fundamental origin of this plasmonic chiroptical response is proposed. The analysis allows the optimization of plasmonic chiroptical materials. [ABSTRACT FROM AUTHOR]

We present a lattice structure defined by patterns of slits that follow a rotational symmetry (chiral) configuration. The chiral pattern of the slits creates a series of hinges that produce deformation mechanisms for the lattice due to bending of the ribs, leading to a marginal negative Poisson's ratio. The engineering constants are modeled using theoretical and numerical Finite Element simulations. The results are benchmarked with experimental data obtained from uniaxial and off-axis tensile tests, with an overall excellent agreement. The chiral hinge lattice is almost one order of magnitude more compliant than other configurations with patterned slits and – in contrast to other chiral micropolar media – exhibits an in-plane shear modulus that closely obeys the relation between Young's modulus and Poisson's ratio in homogeneous isotropic linear elastic materials. [ABSTRACT FROM AUTHOR]

Chiral three‐dimensional hybrid organic–inorganic perovskites (3D HOIPs) would show unique chiroptoelectronic performance due to the combination of chirality and 3D structure. However, the synthesis of 3D chiral HOIPs remains a significant challenge. Herein, we constructed a pair of unprecedented 3D chiral halide perovskitoids (R/S‐BPEA)EA6Pb4Cl15 (1‐R/S) (R/S‐BPEA=(R/S)‐1‐4‐Bromophenylethylammonium, EA=ethylammonium), in which the large chiral cations can be contained in the big "hollow" inorganic frameworks induced by mixing cations. Notably, 3D 1‐R/S shows natural chiroptical activity, as evidenced by its significant mirror circular dichroism spectra and the ability to distinguish circularly polarized light. Moreover, based on the unique 3D structure, 1‐S presents sensitive X‐ray detection performance with a low detection limit of 398 nGyair s−1, which is 14 times lower than the regular medical diagnosis of 5.5 μGyair s−1. In this work, 3D chiral halide perovskitoids provide a new route to develop chiral material in spintronics and optoelectronics. [ABSTRACT FROM AUTHOR]

Multi-particle states with additional pions are expected to result in a difficult-to-control excited-state contamination in lattice simulations. We show that heavy meson chiral perturbation theory can be employed to estimate the contamination due to two-particle B π states in various B-meson observables, like the B-meson decay constant and the B ∗ B π coupling. We work in the static limit and to next-to-leading order in the chiral expansion, i.e. including O (p). The B π states are found to typically lead to an overestimation of the observables at the few percent level. We determine two of the LECs from B → π form factor computations of the KEK group (Colquhoun et al. in Phys. Rev. D 106:054502, 2022) and discuss ways to determine the others. In particular, one LEC which is associated with smeared interpolating fields seems to be easily accessible and thus opens up a way to systematically study the effect of smearing on excited-state effects. [ABSTRACT FROM AUTHOR]

We propose confining dualities of N = (0, 2) half-BPS boundary conditions in 3d N = 2 supersymmetric SU(N), USp(2n) and SO(N) gauge theories. Some of these dualities have the novel feature that one (anti)fundamental chiral has Dirichlet boundary condition while the rest have Neumann boundary conditions. While some of the dualities can be extended to 3d bulk dualities, others should be understood intrinsically as 2d dualities as they seem to hold only at the boundary. The gauge theory Neumann half-indices are well-defined even for theories which contain monopole operators with non-positive scaling dimensions and they are given by Askey-Wilson type q-beta integrals. As a consequence of the confining dualities, new conjectural identities of such integrals are found. [ABSTRACT FROM AUTHOR]

We compute all worldsheet three-point functions involving spectrally-flowed operators in chiral multiplets of the space-time theory for strings in AdS3×S3×T4, thus completing the analysis of the full AdS3/CFT2 chiral ring. We make use of techniques recently developed for the bosonic sector, based on holomorphic covering maps from the worldsheet to the AdS3 boundary. We highlight the role of the so-called series identifications when dealing with the complications originated by picture-changing spectrally-flowed states. We find an exact agreement with the predictions from the holographic CFT at the symmetric orbifold point. [ABSTRACT FROM AUTHOR]

In this paper, we investigate the mass spectra of bottom-charm baryons systematically, where the relativistic quark model and the infinitesimally shifted Gaussian basis function method are employed. Our calculation shows that the ρ -mode appears lower in energy than the other excited modes. According to this feature, the allowed quantum states are selected and a systematic study of the mass spectra for Ξ b c ′ ( Ξ b c ) and Ω b c ′ ( Ω b c ) families is performed. The root mean square radii and quark radial probability density distributions of these baryons are analyzed as well. Next, the Regge trajectories in the (J , M 2) plane are successfully constructed based on the mass spectra. At last, we present the structures of the mass spectra, and analyze the difficulty and opportunity in searching for the ground states of bottom-charm baryons in experiment. [ABSTRACT FROM AUTHOR]

Chiral supramolecular assemblies with helical structures (e. g. proteins with α‐helix, DNA with double helix, collagen with triple‐helix) as the central structure motifs in biological systems play a crucial role in various physiological activities of living organisms. Variations in chiral structure can cause many abnormal physiological activities. To gain insight into the construction, structural transition, and related physiological functions of these complex helix in natural systems, it is necessary to fabricate artificial supramolecular assemblies with controllable helix orientation as research platform. This review discusses recent advances in chiral supramolecular assembly, including the precise construction and regulation of assembled chiral nanostructures with tunable chirality. Chiral structure‐dependent biological activities, including cell proliferation, cell differentiation, antibacterial activity and tissue regeneration, are also discussed. This review not only contributes to further understanding of the importance of chirality in the physiological environment, but also plays an important role in the development of chiral biomedical materials for the treatment of diseases (e. g. tissue engineering regeneration, stem cell transplantation therapy). [ABSTRACT FROM AUTHOR]

Among antiferromagnetic materials, Mn2Au is one of the most intensively studied, and it serves as a very popular platform for testing various ideas related to antiferromagnetic magnetotransport and dynamics. Since recently, this material has also attracted considerable interest in the context of optical properties and optically-driven antiferromagnetic switching. In this work, we use first principles methods to explore the physics of charge photocurrents, spin photocurrents, and the inverse Faraday effect in antiferromagnetic Mn2Au. We predict the symmetry and magnitude of these effects and speculate that they can be used for tracking the dynamics of staggered moments during switching. Our calculations reveal the emergence of large photocurrents of spin in collinear Mn2Au, whose properties can be understood as a result of a non-linear optical version of the spin Hall effect, which we refer to as the photospin Hall effect, encoded into the relation between the driving charge and resulting spin photocurrents. Moreover, we suggest that even a very small canting in Mn2Au can give rise to colossal spin photocurrents that are chiral in flavor. We conclude that the combination of staggered magnetization with the structural and electronic properties of this material results in a unique blend of prominent photocurrents, which makes Mn2Au a unique platform for advanced optospintronics applications. [ABSTRACT FROM AUTHOR]

We revisit the modular weights in type IIB magnetized D-brane models. The simple analysis of wave function shows that the four-dimensional matter fields have the modular weight -1/2, but it may shift as one in type IIA intersecting D-brane models. For example, the localized gauge flux as well as the localized curvature can shift the modular weight in the magnetized D-brane models. Such corrections do not affect physical couplings such as physical Yukawa couplings. However, it leads to differences in supersymmetry breaking sfermion masses, which depend on the modular weights, although the A-term coefficients and the sum of sfermion masses squared seem to be the same between two models. [ABSTRACT FROM AUTHOR]

It is an important question in string compactification whether complex structure moduli stabilization inevitably ends up with a vacuum expectation value of the superpotential W of the order of the Planck scale cubed. Any thoughts on volume stabilization and inflation in string theory, as well as on phenomenology of supersymmetric Standard Models, will be affected by the answer to this question. In this work, we follow an idea for making W ≃ 0 where the internal manifold has a vacuum complex structure with arithmetic characterization, and address Calabi–Yau fourfold compactification of F-theory. The moduli space of K3 × K3 orbifolds contain infinitely many such vacua. Arithmetic conditions for a W = 0 flux are worked out, and then all the K3 moduli have supersymmetric mass. Possible gauge groups, matter representations and discrete symmetries are studied for the case of Z 2 -orbifolds. [ABSTRACT FROM AUTHOR]

Atomistic understanding of thermodynamic processes such as phase transitions in nanoalloys is crucial to improve real-life applications of Pt-based nanocatalysts. In this work, we investigate the thermodynamic properties of 55-atom PtCo and PtNi nanoalloys and compare them to reference unary systems, Pt55, Co55, and Ni55. Our results are based on the combination of the parallel tempering Monte Carlo and the revised basin-hopping Monte Carlo algorithms with many-body Gupta potentials, and furthermore, density functional theory calculations were employed to validate the adopted Gupta parameters and to analyze electronic effects induced by structural changes derived from temperature effects. We identified first-order phase transitions for Pt55, Co55, Pt30Co25, Ni55, and Pt40Ni15 at 727, 1027, 1003, 914, and 1051 K, respectively. Thus, alloying unary Pt nanoclusters with Ni and Co leads to an increase in the melting temperature, indicating that the nanoalloys are able to sustain higher temperatures while maintaining their structure. A low-temperature solid-solid transition was also identified for Pt55, which is characterized by a change from a face-centered cubic like structure (putative global minimum configuration) to the icosahedron structure. The structural transformations led by the temperature increase induce small changes on the total density of states, namely, a slight shift of the d-band center toward the highest occupied molecular orbital with increasing temperature, which was found for all considered nanoclusters. [ABSTRACT FROM AUTHOR]

Chiral magnetic insulators manifest novel phases of matter where the sense of rotation of the magnetization is associated with exotic transport phenomena. Effective control of such phases and their dynamical evolution points to the search and study of chiral fields like the Dzyaloshinskii–Moriya interaction. Here we combine experiments, numerics, and theory to study a zig-zag dipolar lattice as a model of an interface between magnetic in-plane layers with a perpendicular magnetization. The zig-zag lattice comprises two parallel sublattices of dipoles with perpendicular easy plane of rotation. The dipolar energy of the system is exactly separable into a sum of symmetric and antisymmetric long-range exchange interactions between dipoles, where the antisymmetric coupling generates a nonlocal Dzyaloshinskii–Moriya field which stabilizes winding textures with the form of chiral solitons. The Dzyaloshinskii–Moriya interaction acts as a vector potential or gauge field of the magnetic current and gives rise to emergent magnetic and electric fields that allow the manifestation of the magnetoelectric effect in the system. [ABSTRACT FROM AUTHOR]

The recently discovered kagome superconductors AV3Sb5 (A = K, Rb, Cs) exhibit unusual charge-density-wave (CDW) orders with time-reversal and rotational symmetry breaking. One of the most crucial unresolved issues is identifying the symmetry of the superconductivity that develops inside the CDW phase. Theory predicts a variety of unconventional superconducting symmetries with sign-changing and chiral order parameters. Experimentally, however, superconducting phase information in AV3Sb5 is still lacking. Here we report the impurity effects in CsV3Sb5 using electron irradiation as a phase-sensitive probe of superconductivity. Our magnetic penetration depth measurements reveal that with increasing impurities, an anisotropic fully-gapped state changes to an isotropic full-gap state without passing through a nodal state. Furthermore, transport measurements under pressure show that the double superconducting dome in the pressure-temperature phase diagram survives against sufficient impurities. These results support that CsV3Sb5 is a non-chiral, anisotropic s-wave superconductor with no sign change both at ambient and under pressure. In the kagome superconductor CsV3Sb5 the symmetry of the superconducting gap is still in question, both at ambient pressure and under high pressure. Here, via controlled introduction of impurities, the authors report evidence for a non-chiral full superconducting gap with no sign change. [ABSTRACT FROM AUTHOR]

Superconducting vortices are promising traps to confine non-Abelian Majorana quasi-particles. It has been widely believed that bulk-state topology, of either normal-state or superconducting ground-state wavefunctions, is crucial for enabling Majorana zero modes in solid-state systems. This common belief has shaped two major search directions for Majorana modes, in either intrinsic topological superconductors or trivially superconducting topological materials. Here we show that Majorana-carrying superconducting vortex is not exclusive to bulk-state topology, but can arise from topologically trivial quantum materials as well. We predict that the trivial bands in superconducting HgTe-class materials are responsible for inducing anomalous vortex topological physics that goes beyond any existing theoretical paradigms. A feasible scheme of strain-controlled Majorana engineering and experimental signatures for vortex Majorana modes are also discussed. Our work provides new guidelines for vortex-based Majorana search in general superconductors. It is widely believed that bulk-state topology is crucial for enabling Majorana zero modes in solid-state systems. Here, the authors predict that superconducting vortices containing Majorana zero modes can arise from topologically-trivial electronic bands, expanding the pool of materials which may host such phenomena. [ABSTRACT FROM AUTHOR]

Herein, we report on the synthesis and high-performance liquid chromatography (HPLC) resolution of a new atropisomeric C2-symmetry chiral monomer based on the 3,3′-bithiophene core, which was developed to produce novel, inherently oligomeric chiral electroactive materials. The analytical enantioseparation was optimized using the cellulose-type Chiralpak IB-3 column and a mixture of n-hexane–methanol–dichloromethane 90:5:5 (v/v/v) as the mobile phase. During the scale-up of the enantioseparation analytical conditions to a semipreparative level, remarkable deformations in the HPLC profile, such as peak splitting and plateau zones between enantiomeric peaks, were observed. We demonstrate the effects of sample diluent as they relate to distorted peak profiles, as well as provide experimental solutions to prevent the disturbing phenomenon. The optimized chromatographic conditions were exploited to collect milligram amounts of the enantiopure sample, which was submitted to chiroptical and stereochemical characterization studies. [ABSTRACT FROM AUTHOR]

Despite the great progress in research on molecular carbons containing multiple helicenes around one core, realizing the stereoselectivity of carbons containing multiple helicenes around more cores is still a great challenge. Herein, molecular carbon C204 featuring 12‐fold [5]helicenes around four cores was successfully constructed by using nine perylene diimide (PDI) units, and exhibits good solubility and stability. Despite 256 possible stereoisomers caused by the 12‐fold [5]helicenes, we only obtained one pair of enantiomers with D3 symmetry. There are four possible pairs of enantiomers with D3 symmetry, namely 7A, 7B, 7C and 7D. Theoretical and experimental results verify that the obtained structure belongs to 7C, which has the lowest energy. The enantiomers can also be separated by chiral HPLC. These results suggest that choosing PDIs as building blocks can not only improve the solubility and stability but also realize the stereoselectivity and chirality of molecular carbons. [ABSTRACT FROM AUTHOR]

Combining the quark model, the quark-pair-creation mechanism and B(*) K ¯ interaction, we have investigated the near-threshold P-wave Bs states in the framework of the Hamiltonian effective field theory. With the heavy quark flavor symmetry, all the parameters are determined in the Ds sector by fitting the lattice data. The masses of the bottom-strange partners of the D s 0 ∗ 2317 and D s 1 ∗ 2460 are predicted to be M B s 0 ∗ = 5730.2 − 1.5 + 2.4 MeV and M B s 1 ∗ = 5769.6 − 1.6 + 2.4 MeV, respectively, which are well consistent with the lattice QCD component. The two P-wave Bs states are the mixtures of the bare b ¯ s core and B(*) K ¯ component. Moreover, we find a crossing point between the energy levels with and without the interaction Hamiltonian in the finite volume spectrum in the 0+ case, which corresponds to a CDD (Castillejo-Dalitz-Dyson) zero in the T-matrix of the B K ¯ scattering. This CDD zero will help deepen the insights of the near-threshold states and can be examined by future lattice calculation. [ABSTRACT FROM AUTHOR]

Chiral separation has attracted much attention for basic research and industrial applications in analytical chemistry. Generally, chiral separations use natural or artificial chiral-based materials as adsorbents. To improve the precision and efficiency of chiral separation, focus has shifted from natural and synthetic adsorbents to binary combinations of materials. This review specifically summarizes the significant advancements made in natural and artificial chiral adsorbents as promising candidates for diverse drug and biomolecule separation applications as well as the remaining drawbacks and challenges for research on chiral separations. The mechanisms of chiral-based recognition and separation and history and development of natural and artificial chiral-based systems are the focus of this review. Future directions in natural and artificial chiral-based systems for practical separations and other applications are also presented. [ABSTRACT FROM AUTHOR]

Chiral carbon dots (CDs) are a novel luminescent zero‐dimensional carbon‐based nanomaterial with chirality. They not only have the advantages of good biocompatibility, multi‐color‐emission, easy functionalization, but also exhibits highly symmetrical chiral optical characteristics, which broadens their applicability to enantioselectivity of some chiral amino acids like cysteine and lysine, asymmetric catalysis as well as biomedicine in gene expression and antibiosis. In addition, the exploration of the excited state chirality of CDs has developed its excellent circularly polarized luminescence (CPL) properties, opening up a new application scenario like recognition of chiral light sources and anti‐counterfeit printing with information encryption. This review mainly focuses on the mature synthesis approaches of chiral CDs, including chiral ligand method and supramolecular self‐assembly method, then we consider emerging applications of chiral CDs in CPL, biosensing and biological effect. Finally, we concluded with a perspective on the potential challenges and future opportunities of such fascinating chiral CDs. [ABSTRACT FROM AUTHOR]

Doping a gold cluster with a transition metal atom allows the structural diversity of gold clusters to be combined with the distinctive features of high-spin systems. SMMs (single molecule magnets) are a special type of open-shell system with unique features. [1], by the complete active space self-consistent field methods We provided a map for HOMOLUMO energy gaps to insight throw different complete active space CAS (e, o) compositions and different number of gold atoms structuring the studied clusters, along with binding energies correlation relationship with the studied cluster size. [ABSTRACT FROM AUTHOR]

A contrastive investigation of the symmetry aspects of phonons in monolayer chromium trihalides and their Janus structures Y3–Cr2–X3 (X, Y = F, Cl, Br, I) was presented within group theory. We classified all phonon vibration modes at the Brillouin-zone center (Γ) into irreducible representations. The infrared and Raman activity of optic phonons, Raman tensors, and the possible polarization assignments of Raman active phonons are further predicted. We clarify the discrepancy concerning the Raman and infrared activity of optic modes in monolayer CrI3. It is also found that the Raman and infrared spectra are exclusive for X3–Cr2–X3 but coincident for Janus Y3–Cr2–X3. This distinction plays a vital role in optic spectra identification of the Janus Y3–Cr2–X3 monolayer from the X3–Cr2–X3 monolayer. To demonstrate the origin of phonon chirality and magnetism intuitively, we derive the symmetry-matched phonon eigenfunctions and the corresponding schematic representations of the eigenvectors for both the F3–Cr2–I3 and I3–Cr2–I3 monolayers. Our analysis indicates that the spin–phonon coupling, the magneto-optical effect of infrared and Raman active phonons, and the phonon chirality could be observed in the Janus Y3–Cr2–X3 monolayer more easily than in the X3–Cr2–X3 monolayer. Our results thus provide a detailed guiding map for experimental identification and characterization of the Janus Y3–Cr2–X3 monolayer. [ABSTRACT FROM AUTHOR]

The symmetries that protect massless Dirac fermions from a gap opening may become ineffective if the Dirac equation is discretized in space and time, either because of scattering between multiple Dirac cones in the Brillouin zone (fermion doubling) or because of singularities at zone boundaries. Here an implementation of Dirac fermions on a space‐time lattice that removes both obstructions is introduced. The quasi‐energy band structure has a tangent dispersion with a single Dirac cone that cannot be gapped without breaking both time‐reversal and chiral symmetries. It is shown that this topological protection is absent in the familiar single‐cone discretization with a linear sawtooth dispersion, as a consequence of the fact that there the time‐evolution operator is discontinuous at Brillouin zone boundaries. [ABSTRACT FROM AUTHOR]

The recognition of small molecules in hydrophobic cavities in aqueous medium is a fundamental process in molecular biology. Previously, we described the synthesis and conformational switching of enantiopure alleno‐acetylenic cage receptors as well as their application as model systems to study in detail the interplay of space occupancy, conformation, complexation, and chiral recognition in organic solvents. Now, we report the synthesis of three enantiopure alleno‐acetylenic cage receptors functionalized with hydrophilic groups at their surface, which allows an extension of the studies to aqueous media. The new receptors show solvent‐ and guest‐induced binary conformational switching between an 'open' and a 'closed' cage conformation. Importantly, the chiroptical properties of the alleno‐acetylenic receptors are strongly conformation‐dependent, an effect that manifests itself upon guest inclusion. We used electronic circular dichroism titrations to quantitatively study the binding of small organic molecules inside the hydrophobic receptor cavity in methanolic water. [ABSTRACT FROM AUTHOR]

The asymmetric transmission of electromagnetic waves can be flexibly manipulated by chiral metamaterials hybridized with tunable materials or active components. Here, we propose the concept of a direction-reversible tunable asymmetric transmission effect realized by chiral metamaterials. As the proof-of-concept, twisted metallic meta-sheets consisting of split-ring resonators incorporated with active diodes is designed for linearly polarized operation in the microwave region. The direction of asymmetric transmission depending on the working states of the loaded diodes can be switched by the external bias voltage in real-time. At the same time, the reconfigurable metamaterial also shows ability to control the polarization of the transmitted wave. Both the simulation and experimental results demonstrate that this direction-reversible chiral metamaterial can dynamically adjust the propagating direction of waves, showing potential uses for full-space wave manipulation and versatile modulation devices. [ABSTRACT FROM AUTHOR]

Theoretical studies of the theory of nematic superconductivity in doped insulators of the Bi2Se3 family have been reviewed. It is experimentally shown that their transition to the superconducting state is accompanied by spontaneous rotational symmetry breaking. This superconductivity is called nematic superconductivity and is described well by a triplet vector order parameter. The main concepts of the microscopic theory and the Ginzburg–Landau theory for nematic superconductivity have been presented. The competition between possible superconducting order parameters in topological insulators has been discussed. It has been shown that hexagonal distortions of the Fermi surface are necessary for implementing the nematic phase. This phase is very sensitive to disorder because charged impurities reduce the critical temperature. The doping-induced transition from the closed to open Fermi surface affects the competition of superconducting phases. Surface Andreev states in nematic superconductors have been discussed. The phenomenological Ginzburg–Landau theory for the two-component order parameter is derived from the microscopic theory. Using the Ginzburg–Landau theory, it has been shown that the ground state is either the real nematic order parameter with the spontaneous deformation of the lattice or a complex chiral order parameter with spontaneous magnetization. The vector structure of the order parameter is responsible for an unconventional relation between superconductivity and the lattice deformation and magnetization. This leads to strong anisotropy of the second critical field, to the appearance of spin vortices (which can be carried by Kramers pairs of Majorana fermions), and to unconventional Pauli paramagnetism for triplet Cooper pairs. [ABSTRACT FROM AUTHOR]

Molecular dynamics simulations are performed to investigate impurity effects on the changes of packing structures, atomic level pressure, and thermodynamics for icosahedral Ag clusters having 55 and 147 atoms. The simulation results indicate that, doping Cu atoms in different cluster shells can significantly affect their thermal stability and thermodynamic values. For the small size clusters, the doping in the interior apparently releases the stress, and improves the stability. The thermodynamic values of entropy and free energy can be used to indicate the order degree of the packing structures and structural transition. The shape changes are related to the local stresses at elevated temperatures. [ABSTRACT FROM AUTHOR]

We present some exact solutions to the ideal hydrodynamics of a relativistic superfluid with an almost-conformal equation of state. The solutions have stress tensors which are invariant under Lorentz boosts in one direction, and represent superfluid generalisations of the Bjorken and Gubser flows. We also study corrections to the flows in first-order hydrodynamics, arguing that dissipation is dominated by the shear viscosity. We present some simple numerical solutions for these viscous corrections. Finally, we estimate the size of corrections to the flows arising when the spontaneously broken U(1) symmetry responsible for superfluidity is only approximate, giving the corresponding Goldstone boson a small non-zero mass. We find that the massless solutions can still provide good approximations at sufficiently small spatial rapidities. [ABSTRACT FROM AUTHOR]

Chirality depends on particular symmetries. For crystal structures it describes the absence of mirror planes and inversion centers, and in addition to translations, only rotations are allowed as symmetry elements. However, chiral space groups have additional restrictions on the allowed screw rotations as a symmetry element, because they always appear in enantiomorphous pairs. This study classifies and distinguishes the chiral structures and space groups. Chirality is quantified using Hausdorff distances and continuous chirality measures and selected crystal structures are reported. Chirality is discussed for bulk solids and their surfaces. Moreover, the band structure, and thus, the density of states, is found to be affected by the same crystal parameters as chirality. However, it is independent of handedness. The Berry curvature, as a topological measure of the electronic structure, depends on the handedness but is not proof of chirality because it responds to the inversion of a structure. For molecules, optical circular dichroism is one of the most important measures for chirality. Thus, it is proposed in this study that the circular dichroism in the angular distribution of photoelectrons in high symmetry configurations can be used to distinguish the handedness of chiral solids and their surfaces. [ABSTRACT FROM AUTHOR]

We identify the existence of various symmetry-protected topological states in one-dimensional superlattices with periodically modulated hopping amplitudes or on-site potentials, which can be characterized by the quantized Berry phase it or the emergence of a pair of degenerate boundary states. It is shown that there may exist three types of topological phases, which are protected by inversion symmetry, chiral symmetry, and both of them, respectively, depending on the modulations, the odd, or the even modulation period. The connection between the hopping and potential modulations is also discussed. Furthermore, we demonstrate that the topological phase protected by the inversion symmetry can be realized in the interacting boson systems trapped in the same superlattices. The results can very possibly be studied experimentally in superlattice systems engineered with state-of-the-art technologies. [ABSTRACT FROM AUTHOR]

In this paper, a terahertz (THz) metamaterial (MM) is designed to achieve ultra-broadband, highly efficient polarization conversion and asymmetric transmission (AT) for linearly polarized (LP) wave. The MM structure is composed of two orthogonal metallic sub-wavelength grating layers and a sandwiched cross-shaped array layer, in which the orthogonal grating layers are used as polarization filters to enhance AT parameters and the cross-shaped structure functions as the polarization converter. Owing to the coupling between two different cut-wires (CWs) and the excitation of higher-order plasmon mode in the cross-shaped structure, the polarization conversion bandwidth is greatly expanded. Results show that the polarization conversion rate (PCR) of the proposed MM structure can exceed 0.99 from 0.41 to 2.38 THz. The AT parameters are above 0.64 in the range of 0.50–2.41 THz with a relative bandwidth of 131.27%, and the near-perfect AT effect with AT parameter in excess of 0.8 occurs at two bands, from 0.53 to 1.48 THz and from 1.80 to 2.06 THz, with the relative bandwidth of 94.53% and 13.47%, respectively. Comparisons of our results with other published works prove that our proposed MM can provide relatively wider bandwidth and higher AT parameter. Due to the excellent performance, the proposed MM has potential applications in designing THz diodes. [ABSTRACT FROM AUTHOR]

Utilizing molecular dynamics (MD) simulation, the effects of grain size and twin boundary spacings (TBS) on the deformation mechanisms of nano-twinned (NT) Ag-doped Cu alloys are investigated. The doped Ag atoms are segregated to grain boundary affect zone (GBAZ). Both lattice and twining partial dislocations emitted from the amorphous inter-granular layer (GBAZ-segregated domains) are frequently observed, which switch on the strength enhancement and strength softening regime respectively. Consequently, it is hard to relate flow stress with dislocation density. Fortunately, the average flow stress of NT Ag-doped Cu alloy seems to be sensitive to GBAZ phase transition rather than dislocation density. [ABSTRACT FROM AUTHOR]

Substituent effects on singlet (s) and triplet (t), symmetric acyclic (1X), cyclic‐saturated (2X), and cyclic‐unsaturated (3X) diamino(phosphino)phosphinidenes are investigated, at B3LYP/6‐311++G** level of theory (X = H, Me, t‐Bu, NH2, OH, Ph, CF3, and CN). All novel phosphinidenes scrutinized show singlet ground state, suggested by the conductor‐like polarizable continuum model (CPCM) on both gas‐phase and solvent‐phase optimized structures. Singlet–triplet energy gap (ΔES–T) increases in going from acyclic to cyclic‐saturated and cyclic‐unsaturated structures in gas phase. Band gap (ΔEH–L) decreases in going from cyclic‐saturated to cyclic‐unsaturated and to acyclic structures. Proton affinity (PA) decreases in going from acyclic to cyclic‐unsaturated and cyclic‐saturated structures in gas phase. Inverse pKa increases in both polar solvents (water and DMSO). Most our phosphinidenes appear as superacids in gas phase. [ABSTRACT FROM AUTHOR]

In this study, comparative analysis of calculated (GIAO method, DFT level) and experimental 31P NMR shifts for a wide range of model palladium complexes showed that, on the whole, the theory reproduces the experimental data well. The exceptions are the complexes with the P=O phosphorus, for which there is a systematic underestimation of shielding, the value of which depends on the flexibility of the basis sets, especially at the geometry optimization stage. The use of triple-ζ quality basis sets and additional polarization functions at this stage reduces the underestimation of shielding for such phosphorus atoms. To summarize, in practice, for the rapid assessment of 31P NMR shifts, with the exception of the P=O type, a simple PBE0/{6-311G(2d,2p); Pd(SDD)}//PBE0/{6-31+G(d); Pd(SDD)} approximation is quite acceptable (RMSE = 8.9 ppm). Optimal, from the point of view of "price–quality" ratio, is the PBE0/{6-311G(2d,2p); Pd(SDD)}//PBE0/{6-311+G(2d); Pd(SDD)} (RMSE = 8.0 ppm) and the PBE0/{def2-TZVP; Pd(SDD)}//PBE0/{6-311+G(2d); Pd(SDD)} (RMSE = 6.9 ppm) approaches. In all cases, a linear scaling procedure is necessary to minimize systematic errors. [ABSTRACT FROM AUTHOR]

Polyoxometalates (POMs) are polyatomic anions that comprise transition metal group 5 (V, Nb, Ta) or group 6 (Mo, W) oxyanions connected together by shared oxygen atoms. POMs are fascinating because of their exclusive and remarkable characteristics. One of the most interesting features of POMs is their capability to function as an electron relay by performing stepwise multi-electron redox reactions while maintaining their structural integrity. Functionalization of POMs with amino organic compounds results in organoimido derivatives of polyoxometalates, which have aroused interest due to augmentation of their properties. Comprehensive study has shown that the synthesis methodologies to obtain desired organoimido derivatives of POMs by employing various imido-releasing reagents have progressed drastically in recent decades, particularly the innovative DCC-dehydrating technique. These organoimido functionalized POMs have been used as major building blocks to develop unique nanostructured organic–inorganic hybrid molecular materials. Many conventional organic synthesis processes such as Pd-catalyzed carbon–carbon coupling and esterification reactions have been performed with organoimido functionalized POMs where the presence of POM triggered the reaction process. Thus, investigation of the reactivity of organoimido derivatives of POMs foreshadows the intriguing future of POMs chemistry. [ABSTRACT FROM AUTHOR]

In gauge-Higgs unification (GHU), gauge symmetry is dynamically broken by an Aharonov–Bohm (AB) phase, θ H , in the fifth dimension. We analyze SU (2) GHU with an SU (2) doublet fermion in the flat M 4 × (S 1/ Z 2) spacetime and in the Randall–Sundrum (RS) warped space. With orbifold boundary conditions the U (1) part of gauge symmetry remains unbroken at θ H = 0 and π. The fermion multiplet has chiral zero modes at θ H = 0, which become massive at θ H = π. In other words, chiral fermions are transformed to vector-like fermions by the AB phase θ H . The chiral anomaly at θ H = 0 continuously varies as θ H , and vanishes at θ H = π. We demonstrate this intriguing phenomenon in the RS space in which no level crossing occurs in the mass spectrum and everything varies smoothly. The flat spacetime limit is singular as the anti-de Sitter curvature of the RS space diminishes, and reproduces the result in the flat spacetime. Anomalies appear for various combinations of Kaluza–Klein excitation modes of gauge fields as well. Although the magnitude of the anomalies depends on θ H and the warp factor of the RS space, it does not depend on the bulk mass parameter of the fermion field controlling its mass and wave function at general θ H . [ABSTRACT FROM AUTHOR]

This paper employs a non-abelian gauge theory to derive the relation between a chiral crystal structure and the bulk magnetic DMI energy term. We apply the method to the B20 chiral compounds, in which the chirality develops along the diagonals of the cubic crystal, and we derive, in this framework, the corresponding isotropic Lifshitz invariant. [ABSTRACT FROM AUTHOR]

Low energy constants (LECs) of heavy-hadron chiral perturbation theory (HH χ PT) for low lying bottom mesons are computed. The available data for J P = 0 - , 1 - , 0 + and 1 + of bottom mesons are used to analyze the mass formulae of low lying bottom mesons having low energy constants up to one-loop corrections. The decay widths of bottom mesons ( J P = 0 + and 1 + ) are analyzed to constraint the couplings. These coupling constants are used to fix the one-loop corrections in the mass formulae. The masses and couplings are then used to find LECs from mass formulae. The behavior of tree level masses are studied by changing LECs. This study has improved over the infinite number of sets of LECs for low lying bottom meson masses in HH χ PT. [ABSTRACT FROM AUTHOR]

Abstract: We report on a first next-to-next-to-leading order calculation of the decay constants of the D () and B () mesons using a covariant formulation of chiral perturbation theory. It is shown that, using the state-of-the-art lattice QCD results on as input, one can predict quantitatively the ratios of , , and taking into account heavy-quark spin-flavor symmetry breaking effects on the relevant low-energy constants. The predicted relations between these ratios, and , and their light-quark mass dependence should be testable in future lattice QCD simulations, providing a stringent test of our understanding of heavy quark spin-flavor symmetry, chiral symmetry and their breaking patterns. [Copyright &y& Elsevier]

Abstract: We use a superspin Hamiltonian defined on an infinite-dimensional Fock space with positive definite scalar product to study localization and delocalization of noninteracting spinless quasiparticles in quasi-one-dimensional quantum wires perturbed by weak quenched disorder. Past works using this approach have considered a single chain. Here, we extend the formalism to treat a quasi-one-dimensional system: a quantum wire with an arbitrary number of channels coupled by random hopping amplitudes. The computations are carried out explicitly for the case of a chiral quasi-one-dimensional wire with broken time-reversal symmetry (chiral-unitary symmetry class). By treating the space direction along the chains as imaginary time, the effects of the disorder are encoded in the time evolution induced by a single site superspin (non-Hermitian) Hamiltonian. We obtain the density of states near the band center of an infinitely long quantum wire. Our results agree with those based on the Dorokhov–Mello–Pereyra–Kumar equation for the chiral-unitary symmetry class. [Copyright &y& Elsevier]

The article focuses on mechanisms for Chiral recognition. Due to their natural symmetry, chiral compounds show different properties in biochemical systems, but they are not distinguishable in inanimate environments. Two molecules that are mirror images of each other are called an enantiomeric pair, and they show same properties in all isotropic conditions. However, because biochemical systems are not isotropic, the pharmacological effects of two enantiomers of a chiral drug may be different. Due to this, there is a need for chiral recognition mechanism. In the "Three-point interaction model" for chiral recognition, molecular recognition can be done on the basis of differential binding of two enantiomers to a chiral three-point site on the selector. The enantiometer can match a maximum of only two sites, irrespective of how its mirror image rotates. Chiral selection can be done by evaluating the possible interactions, and then designing a selector that would interact differently with an enantiomeric form than with its mirror image. Chiral recognition mechanism is based on the measurement of the binding energy of the two chiral-selector-enantiomer complexes.