Effects Of Long-range Interactions Research Articles

Strange sounds

This latter addresses the effects of long-ranged and/or retarded interactions on the bosonic collective modes in the so-called ‘strange metals’. Recently, there have been conflicting reports on the very existence of such stable collective excitations and their properties. Extending a number of approaches that have been previously used in the analyses of the standard Fermi liquid one finds evidence for, both, conventional and novel behaviors of the non-Fermi-liquid counterparts of the zero-, shear-, and other ‘sounds’.

The effects of long-range interaction to wave propagation

The effects of long-range interaction to wave propagation

Effect of Long-Range Interaction in the Modification of Surface Layers of WC–Co Samples by a Pulsed Ion Beam

The results of modification of WC–Co samples by a pulsed beam of nitrogen ions (200–300 keV, 120 ns) with an energy density of 7–8 J/cm2 are presented. It is shown that the change in the structure occurs in the near-surface layer with a thickness of 20–30 µm, which significantly exceeds the range of ions in the target (≈0.5 µm) and the depth of propagation of the thermal front during the pulse (≈1 µm). The analysis of various mechanisms of the long-range effect is carried out: the formation of a shock wave, the generation of primary radiation defects, etc. It is shown that the long-range effect is associated with the charge exchange of ions and the formation of fast atoms. The simulation of the charge exchange of ions in the gaseous layer of desorbed molecules is performed. It was found that the probability of ion charge exchange in the processes N+ + N2 → N0 and N+ + O2 → N0 significantly exceeds 100%, which indicates that the effect of irradiation by atoms was not taken into account while calculating. In contrast to ions, when the target is irradiated with atoms, the efficiency of the formation of radiation defects is much higher.

Distance plus attention for binding affinity prediction

Protein-ligand binding affinity plays a pivotal role in drug development, particularly in identifying potential ligands for target disease-related proteins. Accurate affinity predictions can significantly reduce both the time and cost involved in drug development. However, highly precise affinity prediction remains a research challenge. A key to improve affinity prediction is to capture interactions between proteins and ligands effectively. Existing deep-learning-based computational approaches use 3D grids, 4D tensors, molecular graphs, or proximity-based adjacency matrices, which are either resource-intensive or do not directly represent potential interactions. In this paper, we propose atomic-level distance features and attention mechanisms to capture better specific protein-ligand interactions based on donor-acceptor relations, hydrophobicity, and π\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\pi $$\\end{document}-stacking atoms. We argue that distances encompass both short-range direct and long-range indirect interaction effects while attention mechanisms capture levels of interaction effects. On the very well-known CASF-2016 dataset, our proposed method, named Distance plus Attention for Affinity Prediction (DAAP), significantly outperforms existing methods by achieving Correlation Coefficient (R) 0.909, Root Mean Squared Error (RMSE) 0.987, Mean Absolute Error (MAE) 0.745, Standard Deviation (SD) 0.988, and Concordance Index (CI) 0.876. The proposed method also shows substantial improvement, around 2% to 37%, on five other benchmark datasets. The program and data are publicly available on the website https://gitlab.com/mahnewton/daap.Scientific Contribution StatementThis study innovatively introducesdistance-based features to predict protein-ligand binding affinity, capitalizing onunique molecular interactions. Furthermore, the incorporation of protein sequencefeatures of specific residues enhances the model’s proficiency in capturing intricatebinding patterns. The predictive capabilities are further strengthened through theuse of a deep learning architecture with attention mechanisms, and an ensembleapproach, averaging the outputs of five models, is implemented to ensure robustand reliable predictions.

Asymmetric magnetization switching and programmable complete Boolean logic enabled by long-range intralayer Dzyaloshinskii-Moriya interaction

After decades of efforts, some fundamental physics for electrical switching of magnetization is still missing. Here, we report the discovery of the long-range intralayer Dzyaloshinskii-Moriya interaction (DMI) effect, which is the chiral coupling of orthogonal magnetic domains within the same magnetic layer via the mediation of an adjacent heavy metal layer. The effective magnetic field of the long-range intralayer DMI on the perpendicular magnetization is out-of-plane and varies with the interfacial DMI constant, the applied in-plane magnetic fields, and the magnetic anisotropy distribution. Striking consequences of the effect include asymmetric current/field switching of perpendicular magnetization, hysteresis loop shift of perpendicular magnetization in the absence of in-plane direct current, and sharp in-plane magnetic field switching of perpendicular magnetization. Utilizing the intralayer DMI, we demonstrate programable, complete Boolean logic operations within a single spin-orbit torque device. These results will stimulate investigation of the long-range intralayer DMI effect in a variety of spintronic devices.

Effect of Long-Range Interaction in the Modification of Near-Surface Layers of WC–Co Samples by Pulsed Ion Beam

Effect of Long-Range Interaction in the Modification of Near-Surface Layers of WC–Co Samples by Pulsed Ion Beam

Mechanosensitivity of phase separation in an elastic gel

Liquid–liquid phase separation (LLPS) in binary or multi-component solutions is a well-studied subject in soft matter with extensive applications in biological systems. In recent years, several experimental studies focused on LLPS of solutes in hydrated gels, where the formation of coexisting domains induces elastic deformations within the gel. While the experimental studies report unique physical characteristics of these systems, such as sensitivity to mechanical forces and stabilization of multiple, periodic phase-separated domains, the theoretical understanding of such systems and the role of long-range interactions have not emphasized the nonlinear nature of the equilibrium binodal for strong segregation of the solute. In this paper, we formulate a generic, mean-field theory of a hydrated gel in the presence of an additional solute which changes the elastic properties of the gel. We derive equations for the equilibrium binodal of the phase separation of the solvent and solute and show that the deformations induced by the solute can result in effective long-range interactions between phase-separating solutes that can either enhance or, in the case of externally applied pressure, suppress phase separation of the solute relative to the case where there is no gel. This causes the coexisting concentrations at the binodal to depend on the system-wide average concentration, in contrast to the situation for phase separation in the absence of the gel.Graphical abstract

Ordered patterns in electroactive polymer ionic liquid blends: effect of long range interactions.

Designing multifunctional soft materials via pattern formation has been a major challenge for scientists and engineers. Soft materials based on polymers are the perfect candidates for designing such materials as they are not only easy to handle, but also offer diverse combinations of mechanical and chemical properties. Here, we present a polymer-based ternary system and reveal, using modelling and simulations, the mechanisms for creating patterned surfaces. Specifically, we consider polymer ionic liquid (PIL) blends and demonstrate that exposure to a uniform electric field results in the formation of ordered patterns through phase separation. Our approach is based on reaction-diffusion phenomena and utilizes Poisson-Boltzmann-Nernst-Planck equations to capture the long-range interactions of ionic liquids in both weak and strong segregation limits. Furthermore, we elucidate that the ordered patterns in our PIL blend can be tuned by changing the direction of the electric field. From the structural characterization point of view, we reveal that the presence of the electric field significantly enhances the domain growth rate and their respective ordering in a remarkable fashion. We believe this non-invasive technique is a significant step towards the development of ordered structures at microscopic length scales and can be utilized for micro-scale fabrication from soft materials.

Crystal-chemical, vibrational and electronic properties of 1M-phlogopite K(Mg,Fe)3Si3AlO10(OH)2 from Density Functional Theory simulations

Trioctahedral micas are peculiar minerals that may present interesting electronic properties that can be modulated by specific cationic substitutions. In the present work, a detailed characterization of the structural, vibrational, and electronic properties of 1M-phlogopite as a function of the FeII/MgII substitutions, with Mg/Fe ratio ≥ 2, is reported. The results were obtained from density functional theory simulations at the B3LYP-D* level of theory, which included the effect of long-range interactions, and also using all-electron Gaussian-type orbitals to describe the atoms in the mineral. The crystal structures of the different phlogopite models were in good agreement with previous X-ray and neutron diffraction data reported in the literature. In addition, the simulated Raman spectra well described the experimental ones obtained from confocal Raman micro-spectrometry, providing additional information on the atomic motions. The electronic band structure and the atom- and orbital-projected density of states were also discussed, describing the nature of the band gap and electronic transitions, and how they vary with the iron content.

A numerical study on the role of dipole interactions on the heat transfer rates in a ferrofluid shear flow

A square partially heated lid-driven cavity filled with ferrofluid subjected to the applied field of a permanent magnet is investigated numerically. These simulations are performed using an in-house code based on the Finite Volume Method. The problem is governed by mass, momentum and energy conservation laws. A phenomenological magnetization equation, which considers the mechanism of long-range dipolar interactions on the scale of the particles, is also used. Laminar steady-state solutions are obtained based on commercial fluids properties and the effects of coupled mechanisms are discussed. A consistent coupling between hydrodynamic, thermal and magnetic effects is observed depending on the particles relaxation time. A high-order model for the equilibrium magnetization, which accounts for the effect of long-range dipolar interactions is considered. The simulations consider particle concentrations of up to 40%. Under such conditions, an enhancement of up to 15% on the average Nusselt number is obtained for Re=100 due to strong dipolar interaction effects. Different combinations for the thermal boundary conditions and lid velocity orientations are considered. A linear relation between the mean Nusselt number and the dipole coupling parameter is observed and justified in terms of scaling arguments.

TiO2-2 RADIATING DAMAGES AS A RESULT OF THE IRRADIATION HELIUM IONS WITH ENERGIES OF 0.12 AND 4 MeV ON THE LINEAR ACCELERATOR

On the linear accelerator of helium ions, the irradiation of TiO2-2 samples with ions energy of 0.12 and 4 MeV to doses of ≈ 1∙1018 ion/cm2 is executed. The elemental composition of TiO2-2 samples is made by roentgenfluorescence method. After irradiation a change of electrophysical characteristics is investigated, microscopic researches on electronic and optical microscopes are conducted. Numerical calculations of atom sputtering ratios taking into account of input angles of helium ions in a sample, and also phonons formation, atoms redistribution (segregation), appearance of the vacancies and displacements in TiO2-2 sample are made. Processes of the flaking formation are investigated, and also presence of the metallization effect and long-range interaction effect in the irradiated samples is shown

Effect of Long-Range Spin-Exchange Interaction in CoPc-Based Two-Dimensional Bimetallic Organic Frameworks for the Electrochemical Reduction of CO2 to CO

Effect of Long-Range Spin-Exchange Interaction in CoPc-Based Two-Dimensional Bimetallic Organic Frameworks for the Electrochemical Reduction of CO₂ to CO

The effect of long-range interactions on the infrared and Raman spectra of aragonite (CaCO3, Pmcn) up to 25 GPa

Long-range interactions are relevant in the physical description of materials, even for those where other stronger bonds give the leading contributions. In this work, we demonstrate this assertion by simulating the infrared and Raman spectra of aragonite, an important calcium carbonate polymorph (space group Pmcn) in geological, biological and materials science fields. To this aim, we used Density Functional Theory methods and two corrections to include long-range interactions (DFT-D2 and DFT-D3). The results were correlated to IR spectroscopy and confocal Raman spectrometry data, finding a very good agreement between theory and experiments. Furthermore, the evolution of the IR/Raman modes up to 25 GPa was described in terms of mode-Grüneisen’s parameters, which are useful for geological and materials science applications of aragonite. Our findings clearly show that weak interactions are of utmost importance when modelling minerals and materials, even when they are not the predominant forces.

Topological effects in two-dimensional quantum emitter systems

In this work we discuss particular effects that take place in systems of quantum emitters coupled to two-dimensional bosonic topological insulators. For a single emitter coupled to the Haldane model, we find a "fragile" quasibound state that makes the emitter dynamics very sensitive to the model's parameters, and gives rise to effective long-range interactions that break time-reversal symmetry. We then discuss one-dimensional arrangements of emitters, emitter line defects, and how the topology of the bath affects the effective polariton models that appear in the weak-coupling regime when the emitters are spectrally tuned to a bandgap. In the Harper-Hofstadter model we link the non-monotonic character of the effective interactions to the Chern numbers of the surrounding energy bands, while in the Haldane model we show that the effective models are either gapless or not depending on the topology of the bath. Last, we discuss how the presence of emitters forming an ordered array, an emitter superlattice, can produce polariton models with non-trivial Chern numbers, and also modify the topology of the photonic states in the bath.

Effect of long range interactions on the reduction of divalent ions in N,O-chelating solvents.

Local processes inside the ion solvation shell are believed to be the main factor affecting ion reduction in battery electrolytes. Much less attention is devoted to the interaction between the ion and molecules outside the shell. We demonstrate that in recently developed divalent batteries, long range ion/solvent and ion/electrode interactions significantly affect the reduction of ions. This effect is caused by the combination of low permittivity solvents, compact solvation shells, and high charge of Mg ions (compared with Li), leading to an effect of up to 1 eV. We establish a connection between our findings and recent experiments, highlighting the potential impact of this effect on battery performance. Additionally, we warn against arbitrarily choosing the dielectric permittivity in cluster-continuum models used for simulations, as even minor uncertainties may lead to significant variations in simulation results for divalent ions.

Effects of long-range inter-particle interactions and isolated defect on quantum walks of two hard-core bosons in one-dimensional lattices

The quantum walk of two hard-core bosons in one-dimensional lattice under the effect of long-range inter-particle interaction is studied in detail. We also simulate the influence of an isolated defect that may exist in the lattice on the quantum walk of two particles by adding an additional potential energy to a certain lattice site. Using exact diagonalization method, the continuous-time quantum walk is directly simulated. The numerical simulations show that the range of interaction (long-range or short-range), the strength of the inter-particle interaction, the initial state of the two particles and the presence of the isolated defect have great influences on the quantum walk. Under the effect of strong long-range interaction, the particles initially located on the non-adjacent lattice sites have a co-walking behavior, while under the short-range interactions (nearest-neighbor interactions) only two particles initially located on the neighboring lattice sites can exhibit co-walking. After introducing the isolated defect into the system with strong interaction, two particles residing on the same side of the isolated defect keep co-walking, while two particles located on either sides of the isolated defect or one particle located on the isolated defect and the other particle staying on the side of the isolated defect, the two particles keep stationary or co-walking near the defect, displaying the characteristics of localization. By using the second-order perturbation theory of degenerate quantum system, a comprehensive theoretical analysis of the above numerical results is given. The theoretical analysis reveals the underlying physical law of quantum walks of two particles in one-dimensional lattice under the effects of strong long-range interaction and isolated defect in the lattice.

Modeling and mitigation of long-range wakefields for advanced linear colliders

The luminosity requirements of TeV-class linear colliders demand use of intense charged beams at high repetition rates. Such features imply multi-bunch operation with long current trains accelerated over the km length scale. Consequently, particle beams are exposed to the mutual parasitic interaction due to the long-range wakefields excited by the leading bunches in the accelerating structures. Such perturbations to the motion induce transverse oscillations of the bunches, potentially leading to instabilities such as transverse beam break-up. Here we present a dedicated tracking code that studies the effects of long-range transverse wakefield interaction among different bunches in linear accelerators. Being described by means of an efficient matrix formalism, such effects can be included while preserving short computational times. As a reference case, we use our code to investigate the performance of a state-of-the-art linear collider currently under design and, in addition, we discuss possible mitigation techniques based on frequency detuning and damping.

Understanding X-ray Photoelectron Spectra of Ionic Liquids: Experiments and Simulations of 1-Butyl-3-methylimidazolium Thiocyanate.

We demonstrate a combined experimental and computational approach to probe the electronic structure and atomic environment of an ionic liquid, based on core level binding energies. The 1-butyl-3-methylimidazolium thiocyanate [C4C1Im][SCN] ionic liquid was studied using ab initio molecular dynamics, and results were compared against previously published and new experimental X-ray photoelectron spectroscopy (XPS) data. The long-held assumption that initial-state effects in XPS dominate the measured binding energies is proven correct, which validates the established premise that the ground state electronic structure of the ionic liquid can be inferred directly from XPS measurements. A regression model based upon site electrostatic potentials and intramolecular bond lengths is shown to account accurately for variations in core-level binding energies within the ionic liquid, demonstrating the important effect of long-range interactions on the core levels and throwing into question the validity of traditional single ion pair ionic liquid calculations for interpreting XPS data.

Cluster expansions of multicomponent ionic materials: Formalism and methodology

The cluster expansion (CE) method has seen continuous and increasing use in the study of configuration-dependent properties of crystalline materials. The original development of the CE method along with the underlying mathematical formalism and assumptions was focused on the study of metallic alloys. Since then the methodology has been actively and successfully used in the study of ionic materials as well. In this work, we present a cohesive reformulation of the mathematical formalism underlying the CE method based on a synthesis of its original formulation, several additions and extensions that have been proposed since, and a revised representation of its constituent mathematical objects. We then proceed to describe some of the formal implications of using the methodology for charge-neutral configurations in ionic systems. In particular, we discuss the reduction of the size of configuration spaces and the resulting linear dependencies that arise among correlation functions that span the larger unconstrained configuration space. Additionally, we explore the effects of long-range electrostatic interactions. We also demonstrate how the previously proposed use of a point electrostatic term successfully accounts for the majority of the longer-range electrostatic interactions, and leaves the cluster expansion terms to capture mostly short-range interactions. Finally, we present and discuss a variety of recently developed methodologies, including training structure selection, oxidation state assignment, structure mapping, and regression algorithms, that are necessary to address these formal mathematical notions for a practical implementation of the CE method in the study of multicomponent ionic materials.

Microscopic Origin of the Effective Spin-Spin Interaction in a Semiconductor Quantum Dot Ensemble

We present a microscopic model for a singly charged quantum dot (QD) ensemble to reveal the origin of the long-range effective interaction between the electron spins in the QDs. Wilson's numerical renormalization group (NRG) is used to calculate the magnitude and the spatial dependency of the effective spin-spin interaction mediated by the growth-induced wetting layer. Surprisingly, we found an antiferromagnetic Heisenberg coupling for very short inter-QD distances that is caused by the significant particle-hole asymmetry of the wetting layer band at very low filling. Using the NRG results obtained from realistic parameters as input for a semiclassical simulation for a large QD ensemble, we demonstrate that the experimentally reported phase shifts in the coherent spin dynamics between single- and two-color laser pumping can be reproduced by our model, solving a long-standing open problem of the microscopic origin of the inter-QD electron spin-spin interaction.