Local Potential Model Research Articles

Structure and transport properties of LiTFSI-based deep eutectic electrolytes from machine-learned interatomic potential simulations.

Deep eutectic solvents have recently gained significant attention as versatile and inexpensive materials with many desirable properties and a wide range of applications. In particular, their characteristics, similar to those of ionic liquids, make them a promising class of liquid electrolytes for electrochemical applications. In this study, we utilized a local equivariant neural network interatomic potential model to study a series of deep eutectic electrolytes based on lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) using molecular dynamics (MD) simulations. The use of equivariant features combined with strict locality results in highly accurate, data-efficient, and scalable interatomic potentials, enabling large-scale MD simulations of these liquids with first-principles accuracy. Comparing the structure of the liquids to the reported results from classical force field (FF) simulations indicates that ion-ion interactions are not accurately characterized by FFs. Furthermore, close contacts between lithium ions, bridged by oxygen atoms of two amide molecules, are observed. The computed cationic transport numbers (t+) and the estimated ratios of Li+-amide lifetime (τLi-amide) to the amide's rotational relaxation time (τR), combined with the ionic conductivity trend, suggest a more structural Li+ transport mechanism in the LiTFSI:urea mixture through the exchange of amide molecules. However, a vehicular mechanism could have a larger contribution to Li+ ion transport in the LiTFSI:N-methylacetamide electrolyte. Moreover, comparable diffusivities of Li+ cation and TFSI- anion and a τLi-amide/τR close to unity indicate that vehicular and solvent-exchange mechanisms have rather equal contributions to Li+ ion transport in the LiTFSI:acetamide system.

Reconciliation of weak pairwise spike-train correlations and highly coherent local field potentials across space.

Multi-electrode arrays covering several square millimeters of neural tissue provide simultaneous access to population signals such as extracellular potentials and spiking activity of one hundred or more individual neurons. The interpretation of the recorded data calls for multiscale computational models with corresponding spatial dimensions and signal predictions. Multi-layer spiking neuron network models of local cortical circuits covering about $1\,{\text{mm}^{2}}$ have been developed, integrating experimentally obtained neuron-type-specific connectivity data and reproducing features of observed in-vivo spiking statistics. Local field potentials can be computed from the simulated spiking activity. We here extend a local network and local field potential model to an area of $4\times 4\,{\text{mm}^{2}}$, preserving the neuron density and introducing distance-dependent connection probabilities and conduction delays. We find that the upscaling procedure preserves the overall spiking statistics of the original model and reproduces asynchronous irregular spiking across populations and weak pairwise spike-train correlations in agreement with experimental recordings from sensory cortex. Also compatible with experimental observations, the correlation of local field potential signals is strong and decays over a distance of several hundred micrometers. Enhanced spatial coherence in the low-gamma band around $50\,\text{Hz}$ may explain the recent report of an apparent band-pass filter effect in the spatial reach of the local field potential.

Theoretical analysis of mixed open-circuit potential for high temperature electrochemical cells electrodes

The Nernst equilibrium potential calculates the theoretical OCV, which estimates the best performance achievable by an electrochemical cell. When multiple semi-reactions (or multiple ionic species) are active in one of the electrodes, the calculation of the theoretical OCV is not straightforward, since different Nernst potentials are associated to each semi-reaction. In this paper, analytical equations for calculation of the theoretical OCV are developed, using the mixed potential theory. The case of H2 and CO co-oxidation (or H2O and CO2 co-reduction) in solid oxide cells is used as a reference case, but similar conclusions can be drawn for other equivalent cases. OCV data from literature are used to calibrate and validate the model. The relative reaction rate of H2 and CO semi-reactions is estimated within the calibration process, and the result is in line with assumptions and suggestions given by other authors. The validation procedure shows predicted OCV values in line with experimental literature data, except for mixtures with relatively large CH4 concentration (e.g., 8%), for which the OCV is significantly underestimated. This is expected when thermochemical reactions, in parallel to electrochemical reactions occur, since the additional H2 produced by internal steam methane reforming is not accounted within the local mixed potential model. A fuel cell polarization model is developed based on the results from the calibration procedure, and it is used to predict the polarization behavior of an SOFC fed with a H2-H2O-CO-CO2 fuel mixture. It is found that either H2 or CO may be reduced rather than oxidized via an equivalent electrochemical water-gas-shift reaction.

Local potential and strategic models in a small market outside the Big Five: the case of Switzerland’s Super League

ABSTRACT Switzerland is a small country of just 8.5 million people. It comprises three distinct language regions and is split into 26 cantons, each of which has a large degree of autonomy. These factors produce a splintered market for sport and clubs are based in areas that vary in terms of their local potential (demographic and economic). Furthermore, soccer clubs face intense competition from another highly popular sport – ice hockey. How clubs exploit a very heterogeneous local potential in a specific context? In this paper, we examine the relationship between a club’s local potential (market environment and stadium) and its expertise in the areas of sporting results, management and marketing. Based on our data, we outline the characteristics of the different economic and sporting models adopted by Switzerland first division soccer clubs and we derive a typology of four types of clubs. Our study’s contribution is both methodological and empirical.

Vibrational Dynamics of Pd-Ni-P Bulk Metallic Glasses: a Local Pseudopotential Study

In the present paper, Phonon modes and elastic constant of three different concentrations of PdxNi1-xP (Pd64Ni16P20, Pd40Ni40P20 and Pd16Ni64P20) bulk metallic glass are calculated using (1) Hubbard-Beeby (HB) and (2) Takeno-Goda (TG) approach along with our well established local model potential. The Hartree (H), Farid et al (F) and Sarkar et al (S) local field correlation functions (LFCF) are employed to examine the effect of the screening function on the collective dynamics of Pd-Ni-P bulk metallic glasses. Results are also reported for phonon dispersion curve, propagation elastic wave and elastic properties viz: bulk modulus BT, modulus of rigidity G, Poisson’s ratio ξ, Young’s modulus Y, Debye temperature ƟD. However, the calculated elastic constants results agree well with other theoretical and available experimental data.

Search for the α + core structure in the ground state bands of 22≤Z≤42 even-even nuclei

A systematic analysis of the $\alpha$ + core structure is performed in the ground state bands of even-even nuclei of the $22 \leq Z \leq 42$ region in terms of the Local Potential Model. The $\alpha$ + core interaction is described by the nuclear potential of (1 + Gaussian)$\times$(W.S. + W.S.$^3$) shape with 2 free parameters. Properties such as energy levels, reduced $\alpha$-widths, $B(E2)$ transition rates and rms charge radii are calculated and compared with experimental data. A good agreement with the experimental data is obtained in general, even for the nuclei without the $\alpha$ + {doubly closed shell core} configuration. The analysis of the selected nuclei in the $22 \leq Z \leq 42$ region indicates that $^{44}$Ti and $^{94}$Mo have a greater $\alpha$-clustering degree in comparison with their respective neighboring nuclei of this set. In addition, the model points to the existence of nuclei without the $\alpha$ + {doubly closed shell core} configuration with a significant $\alpha$-clustering degree compared to $^{44}$Ti, $^{60}$Zn, and $^{94}$Mo. The study shows that the $\alpha$ + core approach is satisfactorily applicable to nuclei other than those with $\alpha$-clustering above double-shell closures.

A new study for healing pitting defects of 316L stainless steel based on microarc technology

A new method for healing corrosion defects was proposed based on the microarc thermal effect, which is enhanced at local geometric defects according to the local additional potential model (LAPM). Finite element analysis (FEA), corrosion tests and surface characterization were used to simulate the principles and evaluate the healing efficiency. The results showed under the microarc effect, the local additional current can be used to detect and heal corrosion defects. This method has an effective healing ability for the initial corrosion defects, and the healed microstructure was composed of recrystallized grains. After being healed, corrosion performance varies slightly.

Geomagnetic Virtual Observatories: monitoring geomagnetic secular variation with the Swarm satellites

We present geomagnetic main field and secular variation time series, at 300 equal-area distributed locations and at 490 km altitude, derived from magnetic field measurements collected by the three Swarm satellites. These Geomagnetic Virtual Observatory (GVO) series provide a convenient means to globally monitor and analyze long-term variations of the geomagnetic field from low-Earth orbit. The series are obtained by robust fits of local Cartesian potential field models to along-track and East–West sums and differences of Swarm satellite data collected within a radius of 700 km of the GVO locations during either 1-monthly or 4-monthly time windows. We describe two GVO data products: (1) ‘Observed Field’ GVO time series, where all observed sources contribute to the estimated values, without any data selection or correction, and (2) ‘Core Field’ GVO time series, where additional data selection is carried out, then de-noising schemes and epoch-by-epoch spherical harmonic analysis are applied to reduce contamination by magnetospheric and ionospheric signals. Secular variation series are provided as annual differences of the Core Field GVOs. We present examples of the resulting Swarm GVO series, assessing their quality through comparisons with ground observatories and geomagnetic field models. In benchmark comparisons with six high-quality mid-to-low latitude ground observatories we find the secular variation of the Core Field GVO field intensities, calculated using annual differences, agrees to an rms of 1.8 nT/yr and 1.2 nT/yr for the 1-monthly and 4-monthly versions, respectively. Regular sampling in space and time, and the availability of data error estimates, makes the GVO series well suited for users wishing to perform data assimilation studies of core dynamics, or to study long-period magnetospheric and ionospheric signals and their induced counterparts. The Swarm GVO time series will be regularly updated, approximately every four months, allowing ready access to the latest secular variation data from the Swarm satellites.

Local potential energy density model (LPE): Applications and limitations to quantify intra/intermolecular interactions

In our previous work, we developed the local potential energy density model, LPE, based on the electrostatic force and QTAIM topological data with a high linearity with the supramolecular binding energy, SME, for the classical hydrogen bonds. In this work, we extended the investigation to other inter/intramolecular interactions. The LPE presented a high linearity with SME when excluding interactions of an ion with π-bonded groups or polar molecule. Due to this linearity, it is possible to obtain the SME of nearly all inter/intramolecular interaction from LPE values. The energy decomposition analysis from SAPT-DFT and LMOEDA showed that dispersion and electrostatic components are important to LPE, while polarization component impairs it. The LPE cannot be used for ions interacting with dipole or dipole or ion interacting with π-bonded systems). In addition, the absolute difference between the numerical values of LPE and SME is very small as in the case of our previous work.

Determination of the Selected Gravity Field Functionals by the GGI Method: A Case Study of the Western Carpathians Area

In this paper, some features of the local disturbing potential model developed by the GGI method (based on Geophysical Gravity Inversion) were analyzed. The model was developed for the area of the Western Carpathians covering the Polish–Slovak border. A detailed assessment of the model’s property was made regarding the accuracy of the disturbing potential values (height anomalies), gravity values, complete Bouguer anomalies (CBA), and differences between geoid undulations and height anomalies (N−ζ). Obtained accuracies of the GGI quasigeoid model (in terms of standard deviation of the residuals to the reference quasigeoid models) were at the level of ±2.2 cm for Poland and ±0.9 cm for the Slovak area. In terms of gravity, there was shown dependence of the accuracy of the GGI model on the digital elevation model (DEM) resolution, the point height, the density of gravity data used, and used reference density of topography model. The best obtained results of gravity prediction were characterized by an error of approximately 1 mGal. The GGI approach were compared with classical gravity prediction methods (using CBA and topographic-isostatic anomalies supported by Kriging prediction), getting very similar results. On the basis of the GGI model, CBA and differences (N−ζ) were also determined. The strong dependence of resolution of the CBA model obtained by GGI approach, on the size of the constant density zones, has been demonstrated. This significantly reduces the quality of such a model. The crucial importance of the topographic masses density model for both determined values (CBA and (N−ζ)) was also indicated. Therefore, for determining these quantities, all available information on topographic mass densities should be used in modelling.

Local disturbing potential model with the use of geophysical gravity data inversion case study in the area of Poland

Local disturbing potential model with the use of geophysical gravity data inversion case study in the area of Poland

Predictions on the α-cluster structure in 104Te

The present work analyzes the α + core structure in 104Te using the local potential model. The α + core interaction is described by a nuclear potential of (1 + Gaussian)×(W.S. + W.S.3) shape. The energy levels, total α widths and rms intercluster separations are determined for the ground state band and compared with a previous calculation which uses a double-folding potential. The two potential forms produce similar spectra between the 0+ and 14+ states. The antistretching effect is predicted for the 104Te ground state band, as is observed in previous α + core calculations in intermediate mass nuclei. An α-decay half-life T1/2,α ≈ 3 ns is predicted for 104Te in the α-decay energy Qα ≈ 5.36 MeV using an α preformation factor P = 1. The calculated T1/2,α value is compatible with the recently reported experimental result on α-decay of 104Te.

Sensitivity of tensor and vector analyzing powers in elastic e-d scattering to modern local and nonlocal NN potentials

In this study, the sensitivity of tensor-deuteron and beam-vector-deuteron analyzing powers in elastic e-d scattering to modern local and nonlocal NN potentials is investigated. We report numerical results for the tensor-deuteron (T20, T21, T22) and beam-vector-deuteron (T10, T11) analyzing powers as functions of the four-momentum transfer square $$Q^2$$ and the electron scattering angle in the laboratory frame $$\theta _e$$ . This could be made possible with the advent of recent polarization measurements with polarized electron beams and polarized deuteron targets at MIT-Bates, JLab, NIKHEF, VEPP-2, and VEPP-3. We found that the estimated results for T20, T21, and T22 are slightly dependent on the local and nonlocal NN potential models adopted for the deuteron wave functions up to $$Q^2\simeq $$ 0.5 (GeV/c) $$^2$$ . At $$Q^2>$$ 0.5 (GeV/c) $$^2$$ , the theoretical discrepancies among various local and nonlocal NN potential models were found. As for the beam-vector-deuteron analyzing powers T10 and T11, we also found that they started to become model dependent when $$Q^2 > $$ 0.5 (GeV/c) $$^2$$ . The considerable dependence of T10 and T11 on the local and nonlocal NN potential models was observed at extremely forward electron angles. The T10 analyzing power was found to be smaller than T11. Therefore, in addition to the single analyzing power T20, the double beam-vector-deuteron analyzing power T11 can be used as another tool for extracting the three deuteron form factors, which provide an intuitive picture of the internal structure of the deuteron. The predicted results for analyzing powers are also compared with the available experimental data and a satisfactory agreement was obtained.

A nonlocal optical model for neutron scattering from light 1p-shell nuclei

Nonlocal effects result in complications when predicting scattering observables. This is usually seen when one analyses the data for nucleon scattering off light 1p-shell nuclei using local optical model potentials. In this work we employ the nonlocal optical model of Perey and Buck (1962) [10] to study the neutron-light nucleus scattering process. By fitting the individual elastic angular distributions we determine energy-dependent, target-specific potential parameters. Then, for each nucleus, a constant set of nonlocal parameters is obtained by simultaneously fitting the corresponding elastic angular distributions. The good quality of the fits prompted us to search for a global constant set of nonlocal parameters by simultaneously fitting a large number elastic angular distribution sets for neutron scattering off light nuclei from 6Li to 18O over the energy range 9 to 35 MeV. We also show that the implicit inclusion of nonlocality in the optical model does not fully remove the need for energy-dependent potential parameters. This is achieved by expressing the nonlocal imaginary volume and surface depths of the constant global set as linear functions of energy and the asymmetry term. The effectiveness of this set is tested by applying it to additional light nuclei and energies outside the fitted range. The predicted elastic angular distributions compared well with the measured data.

α-Cluster structure above double-shell closures and α-decay of 104Te

An analysis of the α+core properties of 104Te along with a global discussion on the α-cluster structure above the double-shell closures is presented from the viewpoint of the local potential model. The α+core interaction is described by a nuclear potential of (1 + Gaussian)×(W.S. + W.S.3) shape with two free parameters, which has been successfully tested in nuclei of different mass regions. The model produces Qα values and α-decay half-lives for 104Te in agreement with the 2018 experimental data of Auranen et al. in the energy range 5.13 MeV<Qα<5.3 MeV using an α preformation factor Pα=1. The comparison of the calculated reduced α-widths for the ground state bands of 104Te, 94Mo and 212Po indicates that 104Te has an α-cluster degree significantly higher than 94Mo and much higher than 212Po. These results point to 104Te as a preferential nucleus for α-clustering in the N,Z=50 region and corroborate the statement on the superallowed α-decay in 104Te.

Calculation energy levels and charge radius for odd 41–49Ca isotopes by using the analytical approach

In this study, some static properties of odd isotopes of Ca were investigated in the non-relativistic shell model. We also suggested a novel suitable local potential model for the non-microscopic investigation of the mentioned nuclei. We modeled the odd [Formula: see text]Ca nuclei as doubly-magic isotopes with further nucleons (valence) in the [Formula: see text] and [Formula: see text] levels. Then, the modified Eckart potential plus Hulthen potential were chosen for the interaction between core and nucleons. We also used the parametric Nikiforov–Uvarov method to calculate the values of energy, the radius of charge and wave function. The obtained results showed a good agreement with the experimental data, so this model is applicable for the similar nuclei.

Deciphering the Contribution of Oriens-Lacunosum/Moleculare (OLM) Cells to Intrinsic θ Rhythms Using Biophysical Local Field Potential (LFP) Models.

Oscillations in local field potentials (LFPs) are prevalent and contribute to brain function. An understanding of the cellular correlates and pathways affecting LFPs is needed, but many overlapping pathways in vivo make this difficult to achieve. A prevalent LFP rhythm in the hippocampus associated with memory processing and spatial navigation is the θ (3–12 Hz) oscillation. θ rhythms emerge intrinsically in an in vitro whole hippocampus preparation and this reduced preparation makes it possible to assess the contribution of different cell types to LFP generation. We focus on oriens-lacunosum/moleculare (OLM) cells as a major class of interneurons in the hippocampus. OLM cells can influence pyramidal (PYR) cells through two distinct pathways: by direct inhibition of PYR cell distal dendrites, and by indirect disinhibition of PYR cell proximal dendrites. We use previous inhibitory network models and build biophysical LFP models using volume conductor theory. We examine the effect of OLM cells to ongoing intrinsic LFP θ rhythms by directly comparing our model LFP features with experiment. We find that OLM cell inputs regulate the robustness of LFP responses without affecting their average power and that this robust response depends on coactivation of distal inhibition and basal excitation. We use our models to estimate the spatial extent of the region generating LFP θ rhythms, leading us to predict that about 22,000 PYR cells participate in intrinsic θ generation. Besides obtaining an understanding of OLM cell contributions to intrinsic LFP θ rhythms, our work can help decipher cellular correlates of in vivo LFPs.

Astrophysical S-factor of the [formula omitted] reaction in the Big-Bang nucleosynthesis

In the present work, we have studied the properties of the 23He(α,γ)47Be reaction. The direct radiative capture nuclear reactions in the Big-Bang nucleosynthesis mainly, are done in the external areas of inter-nuclear interaction range and play an essential role in nuclear astrophysics. Among of these reactions, the 23He(α,γ)47Be reaction with Q = 1.586 MeV is the main part of the Big-Bang nucleosynthesis chain reactions. This reaction can be used to understand the physical and chemical properties of the sun as well as can be justified the lake of the observed solar neutrino in the detector of the Earth. Since product neutrino fluxes are predicated in the center of the sun by the decay of 7Be and 8B, and almost are proportional to the astrophysical S-factor for the 23He(α,γ)47Be reaction, S34. The 23He(α,γ)47Be reaction is considered the key to solve the solar neutrino puzzle. Finally, we have astrophysical S-factor obtained for the ground S1,3/2-, first excited S1,1/2-and total S34 states by modern nucleon-nucleon two-body local potential models. We have also compared the obtained S-factor with experimental data and other theoretical works.

Search for $\alpha$ α + core states in even-even Cr isotopes

The $\alpha + \mathrm{core}$ structure is investigated in even-even Cr isotopes from the viewpoint of the local potential model. The comparison of $Q_{\alpha}/A$ values for even-even Cr isotopes and even-even $A = 46,54,56,58$ isobars indicates that $^{46}$Cr and $^{54}$Cr are the most favorable even-even Cr isotopes for $\alpha$-clustering. The ground state bands of the two Cr isotopes are calculated through a local $\alpha + \mathrm{core}$ potential with two variable parameters. The calculated spectra give a very good description of most experimental $^{46}$Cr and $^{54}$Cr levels. The reduced $\alpha $-widths, rms intercluster separations and $B(E2)$ transition rates are determined for the ground state bands. The calculations reproduce the order of magnitude of the available experimental $B(E2)$ values without using effective charges and indicate that the first members of the ground state bands present a stronger $\alpha$-cluster character. The volume integral per nucleon pair and rms radius obtained for the $\alpha+^{50}$Ti potential are consistent with those reported previously in the analysis of $\alpha$ elastic scattering on $^{50}$Ti.

Quantum dynamics study on the binding of a positron to vibrationally excited states of hydrogen cyanide molecule

We present computational results of vibrationally enhanced positron annihilation in the e++HCN/DCN collisions within a local complex potential model. Vibrationally elastic and inelastic cross sections and effective annihilation rates were calculated by solving a time-dependent complex-potential Schrödinger equation under the ab initio potential energy surface for the positron attached HCN molecule, [HCN; e+], with multi-component configuration interaction level (Kita and Tachikawa, 2014). We discuss the effect of vibrational excitation on the positron affinities from the obtained vibrational resonance features.