Choice Of Potential Research Articles

G Factor of Lithiumlike Silicon and Calcium: Resolving the Disagreement between Theory and Experiment.

The bound-electron g factor is a stringent tool for tests of the standard model and the search for new physics. The comparison between an experiment on the g factor of lithiumlike silicon and the two recent theoretical values revealed the discrepancies of 1.7σ [Glazov etal. Phys. Rev. Lett. 123, 173001 (2019)PRLTAO0031-900710.1103/PhysRevLett.123.173001] and 5.2σ [Yerokhin etal. Phys. Rev. A 102, 022815 (2020)PLRAAN2469-992610.1103/PhysRevA.102.022815]. To identify the reason for this disagreement, we accomplish large-scale high-precision computation of the interelectronic-interaction and many-electron QED corrections. The calculations are performed within the extended Furry picture of QED, and the dependence of the final values on the choice of the binding potential is carefully analyzed. As a result, we significantly improve the agreement between the theory and experiment for the g factor of lithiumlike silicon. We also report the most accurate theoretical prediction to date for lithiumlike calcium, which perfectly agrees with the experimental value.

Spin correlation coefficients in lepton–deuteron elastic scattering and their sensitivity to realistic NN potentials

Spin correlation coefficients in the elastic scattering of leptons on the deuteron, [Formula: see text], are studied in the one-photon-exchange approximation within the limit of zero lepton mass. Numerical estimations for the spin correlation coefficients caused by a polarized beam and a vector polarized target are given. The estimated spin correlation coefficients are analyzed at various values of beam energy and scattering angle. The sensitivity of the obtained results to the choice of realistic NN potential used for the deuteron wave function is investigated. We found a considerable dependence of the results on the realistic deuteron wave functions at incident beam energies greater than 0.4 GeV and backward scattering angles. The estimated results are of particular interest for encouragement of experimental measurements of lepton–deuteron scattering which aim for accurate calculation of the charge radius of the proton to a high degree of precision. These results may also stimulate new generation of measurements of different physical observables very sensitive to the spin structure of the nucleon and light nuclei.

Polarization observables in elastic lepton-deuteron scattering and their sensitivity to realistic NN potentials

Polarization effects in the elastic lepton scattering on the deuteron process are studied in the one-photon-exchange Born approximation within the limit of zero mass of the lepton. Numerical estimations for the spin asymmetries with an unpolarized lepton beam and a tensor polarized target are given. The estimated results are analysed at various lepton beam energies and scattering angles. For the first time, the sensitivity of the results for tensor spin asymmetries to the choice of modern NN potential used for the deuteron wave function (DWF) is investigated. A considerable influence of the results on the realistic and modern DWFs at incident beam energies greater than 0.6 GeV and scattering angles greater than 30 is obtained.

Modeling of Deformation and Destruction Processes of Al/Cu Nanocomposites

The aim of this work is to carry out molecular dynamics simulation of the uniaxial stretching of a cooled Al/Cu composition. The LAMMPS software package has been used for calculations, which includes the classic molecular dynamics code with an emphasis on modeling materials. The Ovito program has been used for visualization, which has a large number of functions, so that the user can thoroughly investigate the results obtained. When describing the interatomic interaction in the Al/Cu nanocomposite, we used the potential of the embedded EAM atom. The choice of potential is due to the fact that it adequately describes and reproduces the properties of a wide class of materials, including metals, semiconductors and alloys. The simulation has been carried out in two stages. At the first stage, a sample consisting of two crystallites of aluminum and copper in the form of parallelepipeds, connected along one of the joint boundaries, was placed in the computational domain and cooled at constant pressure. Cooling was carried out to stabilize the nanosystem. At the second stage, corresponding to the deformation, the temperature and pressure were changed in accordance with the ongoing physical processes. The algorithm of the thermostat and the Nose – Hoover barostat has been used to control the temperature and pressure at the initial stage of cooling. The paper demonstrates the nature of the distribution of longitudinal stresses over the entire volume of the crystal in the process of stretching. When the sample reached the elastic limit, the nucleation of crystal lattice defects and their distribution over the crystal in the form of shifts and rotations of atoms in crystal planes were observed. Areas of plastic deformation origin have been determined. The maximum destruction of the material occurred along the interface. The parameters of the Al/Cu composition (deformation, temperature, mechanical stress) have been dynamically investigated using molecular dynamics simulation. Comparison of the characteristics of the sample in the deformation process has been carried. Under loading conditions, a variety of processes are implemented in the material, including generation of defects, elastic and plastic deformation, generation of damage, and mechanical mixing.

On the planar free energy of matrix models

In this work we obtain the planar free energy for the Hermitian one-matrix model with various choices of the potential. We accomplish this by applying an approach that bypasses the usual diagonalization of the matrices and the introduction of the eigenvalue density, to directly zero in the evaluation of the planar free energy. In the first part of the paper, we focus on potentials with finitely many terms. For various choices of potentials, we manage to find closed expressions for the planar free energy, and in some cases determine or bound their radius of convergence as a series in the ’t Hooft coupling. In the second part of the paper we consider specific examples of potentials with infinitely many terms, that arise in the study of mathcal{N} = 2 super Yang-Mills theories on S4, via supersymmetric localization. In particular, we manage to write the planar free energy of two non-conformal examples: SU(N) with Nf < 2N, and mathcal{N} = 2*.

Deep learning molecular dynamics simulation on microwave high-temperature dielectric function of silicon nitride

Silicon nitride (&lt;i&gt;β&lt;/i&gt;-Si&lt;sub&gt;3&lt;/sub&gt;N&lt;sub&gt;4&lt;/sub&gt;) is a most promising thermal wave-transparent material. The accurate measurement of its high-temperature dielectric function is essential to solving the “black barrier” problem of hypersonic vehicles and accelerating the design of silicon nitride-based thermal wave-transparent materials. Direct experimental measurement at high temperature is a difficult job and the accuracy of classical molecular dynamics (CMD) simulations suffers the choice of empirical potential. In this work, we build a &lt;i&gt;β&lt;/i&gt;-Si&lt;sub&gt;3&lt;/sub&gt;N&lt;sub&gt;4&lt;/sub&gt; model on a nanoscale, train the deep learning potential (DLP) by using first-principles data, and apply the deep potential molecular dynamics (DPMD) to simulate the polarization relaxation process. The predicted energy and force by DLP are excellently consistent with first-principles calculations, which proves the high accuracy of DLP. The RMSEs for &lt;i&gt;β&lt;/i&gt;-Si&lt;sub&gt;3&lt;/sub&gt;N&lt;sub&gt;4&lt;/sub&gt; are quite low (0.00550 meV/atom for energy and 7.800 meV/Å for force). According to the Cole-Cole formula, the microwave dielectric function in the temperature range of 300–1000 K is calculated by using the deep learning molecular dynamics method. Compared with the empirical potential, the computational results of the DLP are consistent with the experimental results in the sense of order of magnitude. It is also found that the DPMD performs well in terms of computational speed. In addition, a mathematical model of the temperature dependence of the relaxation time is established to reveal the pattern of relaxation time varying with temperature. The high-temperature microwave dielectric function of silicon nitride is calculated by implementing large-scale and high-precision molecular dynamics simulations. It provides fundamental data for promoting the application of silicon nitride in high-temperature thermal transmission.

Measuring the Milky Way mass distribution in the presence of the LMC

ABSTRACTThe ongoing interaction between the Milky Way (MW) and its largest satellite – the Large Magellanic Cloud (LMC) – creates a significant perturbation in the distribution and kinematics of distant halo stars, globular clusters and satellite galaxies, and leads to biases in MW mass estimates from these tracer populations. We present a method for compensating these perturbations for any choice of MW potential by computing the past trajectory of LMC and MW and then integrating the orbits of tracer objects back in time until the influence of the LMC is negligible, at which point the equilibrium approximation can be used with any standard dynamical modelling approach. We add this orbit-rewinding step to the mass estimation approach based on simultaneous fitting of the potential and the distribution function of tracers, and apply it to two data sets with the latest Gaia EDR3 measurements of 6D phase-space coordinates: globular clusters and satellite galaxies. We find that models with LMC mass in the range $(1\!-\!2) \times 10^{11}\, \mathrm{M}_\odot$ better fit the observed distribution of tracers, and measure MW mass within 100 kpc to be $(0.75\pm 0.1)\times 10^{12}\, \mathrm{M}_\odot$, while neglecting the LMC perturbation increases it by ∼15 per cent.

Demosthenes’ strategic maneuvering in theFirst Olynthiac

AbstractThe article focuses on the analysis of Demosthenes’ strategic maneuvering in theFirst Olynthiacdelivered in the Athenian Assembly of the People in 349 BC. It is a case study of the famous § 24 in which Demosthenes calls for the attack on Philip of Macedonia, based on a hypothetical reciprocal scenario: Philip would attack Athens in a similar situation. The first part of the paper offers an argumentative characterisation of the Assembly of the People. Subsequently, the historical and situational circumstances of the speech are described, and an argumentative reconstruction of Demosthenes’ speech is presented. The evaluation of the speech’s context serves as a reference point for the analysis of strategic maneuvering by putting forward the argument in § 24. The argument is analysed in terms of three strategic maneuvering aspects: choice of topical potential, adaptation to audience demands, and presentational devices.

Thermodynamically controlled photo-electrochemical CO2 reduction at Cu/rGO/PVP/Nafion multi-layered dark cathode for selective production of formaldehyde and acetaldehyde

Transforming greenhouse gases such as CO2 to energy rich carbon-based chemicals is considered as one of the most efficient technologies for environmental and energy sustainability. However, CO2 is highly stable molecule and difficult to reduce due to its linear structure. The rate of reduction and the nature of fuel product depend on the kinetics and thermodynamics of involved reactions. While the overall reaction kinetics depends on the energy of activated CO2 molecule and its subsequent transition states along with reduction dynamics. Here we demonstrate that by activation of thermodynamically stable CO2 molecule through complexation or coordination with suitable activator such as N-heterocyclic polymers (e.g., poly(4-vinyl)pyridine, PVP), both the kinetics and thermodynamics of photoelectrochemical CO2 reduction reaction can be controlled by proper choice of electrode materials and bias potential. We present a solar light driven photoelectrochemical process for producing formaldehyde and acetaldehyde selectively on multi-layered Cu/rGO/PVP/Nafion hybrid cathode.

Reheating constraints on k -inflation

In this work we revisit constraints on K-inflation with DBI kinetic term and power-law kinetic term from reheating. For DBI kinetic term we choose monomial potentials, $V\propto \phi^n$ with $n=2/3\,,1\,,\,2$ and $4$, and natural inflaton potential, and for power-law kinetic term we choose quadratic, quartic and exponential potentials. The phase of reheating can be parameterized in terms of reheating temperature $T_{re}$, number of e-folds during reheating $N_{re}$ and effective equation of state during reheating $w_{re}$. These parameters can be related to the spectral index $n_s$ and other inflationary parameters depending on the choice of inflaton kinetic term and potential. By demanding that $w_{re}$ should have a finite range and $T_{re}$ should be above electroweak scale, one can obtain the bounds on $n_s$ that can provide bounds on tensor-to-scalar ratio $r$. We find, for K-inflation with DBI kinetic term and quadratic and quartic potentials, that the upper bound on $r$ for physically plausible value of $0\le w_{re} \le 0.25$ is slightly larger than the Planck-2018 and BICEP2/Keck array bound, and for $n=2/3$ and $1$, the reheating equation of state should be less than $0$ to satisfy Planck-2018 joint constraints on $n_s$ and $r$. However, natural inflation with DBI kinetic term is compatible with Planck-2018 bounds on $r$ and joint constraints on $n_s$ and $r$ for physically plausible range $0 \le w_{re}\le 0.25$. The quadratic and quartic potential with power-law kinetic term are also compatible with Planck-2018 joint constraints on $n_s$ and $r$ for $0\le w_{re} \le 1$. However, for exponential potential with power-law kinetic term, the equation of state during reheating $w_{re}$ should be greater than $1$ for $r-n_s$ predictions to lie within $68\%$C.L. of joint constraints on $n_s$ and $r$ from Planck-2018 observations.

Towards highly accurate calculations of parity violation in chiral molecules: relativistic coupled-cluster theory including QED-effects

Parity-violating energies of the H2X2 (X = O, S, Se, Te, Po) molecules are reported, calculated as analytical expectation values at the relativistic coupled-cluster singles-and-doubles (CCSD) level using property-optimised basis sets. Radiative corrections to the was investigated using effective QED-potentials and found to reach a maximal value of 2.38% for H2Po2. However, this result depends on the choice of effective self-energy potential and may indicate limitations to their domain of validity.

Charged stars in 4D Einstein\u2013Gauss\u2013Bonnet gravity

An alternative gravity theory that has attracted considerable attention recently is the novel four-dimensional Einstein–Gauss–Bonnet (4EGB) gravity. This idea was proposed to bypass the Lovelock’s theorem and to permit nontrivial higher curvature effects on the four-dimensional local gravity. In this approach, the Gauss–Bonnet (GB) coupling constant alpha is rescaled by a factor of alpha /(D -4) in D dimensions and taking the limit D rightarrow 4. In this article, we analyze the effects of charge on static compact stars in the regularized 4D EGB gravity theory. Two classes of new exact solutions are found for a particular choice of the gravitational potential and assuming a relationship between the electric field intensity and the spatial potential. A graphical analysis indicates that the matter and electromagnetic variables are well behaved for specific values of the parameter space. Finally, based on physical grounds appropriate bounds on the model parameters we show that compact objects with the value of adiabatic index gamma is consistent with expectations.

Le RNAseq en oncologie de routine

High throughput RNA sequencing, also know as RNAseq, can easily be performed on the gold-standard technique of formalin-fixed paraffin-embedded tissue, which has long been successfully used in routine practice by pathologists. For this reason, RNAseq has been fully adopted in a very short period of time in most French molecular platforms of cancer genotyping, generating "high throughput" data, both qualitative (mutations, fusions) and quantitative (gene expression profiles). This technique opens new perspectives in oncology practice: from a diagnostic point of view (some gene fusions are specific of some diagnoses, some transcriptomic signatures suggest some types of cancer), but also from a prognostic point of view (gene expression profile of an aggressive tumor, or conversely of an indolent one), and above all from a predictive point of view, guiding the choice of potential targeted therapies (example of ALK, ROS1 or NTRK translocations). This technical approach has many advantages, first and foremost it detects, at one go, a plethora of molecular alterations which were previously analyzed sequentially using heterogenous assays (immunohistochemistry, DNA genotyping, fluorescent in situ hybridization, etc.). However, it also presents several drawbacks which may easily be overcome if certain pre-analytic parameters are correctly controlled, mainly aiming at the preservation of the quality of nucleic acids. In any event, the widespread use of RNAseq has had a profound impact on the algorithms of tumor tissue processing, shaping a new, holistic era in oncology.

On the Accuracy of QM/MM Models: A Systematic Study of Intramolecular Proton Transfer Reactions of Amino Acids in Water.

This work presents a systematic assessment of QM/QM' and QM/MM models with respect to direct QM calculations for the tautomerization (neutral to zwitterion) reactions of amino acids (glycine, alanine, valine, aspartate, and neutral and protonated histidine) solvated in a 160 water cluster. The effect of varying QM region size and choice of embedding potentials, including fixed-charge and polarizable molecular mechanics force fields (TIP3P and EFP) and various semiempirical QM methods (PM7, GFN2-xTB, DFTBA, DFTB3, HF-3c, and PBEh-3c), on the accuracy of the models was examined. A surprising finding was that molecular mechanics force fields outperformed many of the semiempirical methods. Generally, the errors in the QM/QM' and QM/MM models converge slowly with respect to the QM region size, requiring 50 or more waters to be included in the QM region before the error in the model falls below 1 kcal mol-1 of its pure QM result. Different QM region selection schemes were also compared, and it was found that selection based on Natural Population Analysis (NPA) atomic charges significantly reduced the error in the QM/QM' and QM/MM models particularly if a low-quality embedding potential was used. It is envisaged that these results will be useful for the development of future hybrid QM models.

Closed-Form Coexistence Equation for Phase Separation of Polymeric Mixtures in Dissipative Particle Dynamics.

To date, no extensive study of the phase diagram for binary fluid mixtures in dissipative particle dynamics (DPD) has been published. This is especially pertinent for newer parameterization schemes where the self-self interaction, or the effective volume, of different particle types is varied. This work presents an exhaustive study of the parameter space concerning DPD particles with soft interaction potentials. Moreover, we propose a closed-form coexistence equation or binodal curve that is inspired by the Flory-Huggins model. This equation describes the phase diagram of all binary mixtures made up out of monomers, homopolymers, and the mixtures thereof when self-self interactions are varied. The mean absolute percentage error (MAPE) of the equation on simulated data, including validation simulations, is 1.02%. The equation can a priori predict the phase separation of mixtures using only DPD interaction parameters. The proposed coexistence equation can therefore be used to directly validate interaction parameters resulting from novel parameterization schemes, including coarse graining and equations of state, without the need for additional simulations. Finally, it is shown that the choice of bond potential markedly influences phase behavior.

Structure and isotropy of lattice pressure tensors for multirange potentials.

We systematically analyze the tensorial structure of the lattice pressure tensors for a class of multiphase lattice Boltzmann models (LBM) with multirange interactions. Due to lattice discrete effects, we show that the built-in isotropy properties of the lattice interaction forces are not necessarily mirrored in the corresponding lattice pressure tensor. This finding opens a different perspective for constructing forcing schemes, achieving the desired isotropy in the lattice pressure tensors via a suitable choice of multirange potentials. As an immediate application, the obtained LBM forcing schemes are tested via numerical simulations of nonideal equilibrium interfaces and are shown to yield weaker and less spatially extended spurious currents with respect to forcing schemes obtained by forcing isotropy requirements only. From a general perspective, the proposed analysis yields an approach for implementing forcing symmetries, never explored so far in the framework of the Shan-Chen method for LBM. We argue this will be beneficial for future studies of nonideal interfaces.

Deviation from Slow-Roll Regime in the EGB Inflationary Models with r ∼ Ne−1

We consider Einstein–Gauss–Bonnet (EGB) inflationary models using the effective potential approach. We present evolution equations in the slow-roll regime using the effective potential and the tensor-to-scalar ratio. The choice of the effective potential is related to an expression of the spectral index in terms of e-folding number Ne. The satisfaction of the slow-roll regime is mostly related to the form of the tensor-to-scalar ratio r. The case of r∼1/Ne2 leads to a generalization of α-attractors inflationary parameters to Einstein–Gauss–Bonnet gravity with exponential effective potential. Moreover, the cosmological attractors include models with r∼1/Ne. And we check the satisfaction of the slow-roll regime during inflation for models with r∼1/Ne.

Mass varying neutrinos with different quintessence potentials

The mass-varying neutrino scenario is analyzed for three trial quintessence potentials (Ferreira-Joyce, inverse exponential,and thawing oscillating).The neutrino mass is generated via Yukawa coupling to the scalar field which represents dark energy.The inverse exponential and oscillating potentials are shown to successfully generate the neutrino masses in the range m ∼ 10-2-10-3 eVand to yield the current dark energy density in the regime of the late-time acceleration of the Universe.Depending on the choice of potentials, the acceleration could occur in two different regimes:(1) the regime of instability, and (2) the stable regime. The first regime of instability is after the Universe underwent a first-order transition and is rolling toward the new stable vacuum. The imaginary sound velocity c2 s < 0 in this regime implies growing fluctuations of the neutrino density (clustering). In the second regime, the Universe smoothly changes its stable states via a continuous transition. Since c2 s > 0, the neutrino density is stable.For all cases the predicted late-time acceleration of the Universe is asymptotically very close to that of the ΛCDM model.Further extensions of the theory to modify the neutrino sector of the Standard Model and to incorporate inflation are also discussed.It is also shown that in the stable regimes where the neutrino mass is given by the minimum of the thermodynamic potential, the tree-level dynamics of the scalar field is robust with respect to one-loop bosonic and fermionic corrections to the potential.

Role of time reversal symmetry and tilting in circular photogalvanic responses

We study the role of time reversal symmetry (TRS) in the circular photogalvanic (CPG) responses considering chiral Weyl semimetal (WSM) while a quantized CPG response is guaranteed by broken of both inversion symmetry (IS) and mirror symmetries. The TRS broken WSM yields one left and one right chiral Weyl nodes (WNs) while there are two left and right chiral WNs for TRS invariant WSM. We show that these features can potentially cause the quantization of CPG response at higher values compared to the topological charge of the underlying WSM. This is further supported by the fact that Berry curvature and velocity behave differently whether the system preserves or breaks the TRS. We find the CPG responses for TRS invariant type-II WSM to be quantized at two and four times the topological charge of the activated WNs while the chemical potential are respectively chosen in the vicinity of energies associated with left and right chiral WNs. By contrast, irrespective of the above choice of the chemical potential, the quantization in CPG response is directly given by the topological charge of the activated WNs for TRS broken case. Interestingly, we notice non-quantized peak in CPG response when energies of WNs associated with opposite chiralities are close to each other as it is the case for TRS invariant type-I WSM considered here. Moreover, we show that the tilt can significantly modify the CPG response as velocity in the tilt direction changes which enters into the CPG tensor through the Fermi distribution function. Given these exciting outcomes, the second order CPG response emerges as a useful indicator to characterize the system under consideration. Furthermore, we investigate the momentum resolved structure of CPG response to relate with the final results and strengthen our analysis from the perspective of the lattice models.

Nonmonotonic confining potential and eigenvalue density transition for generalized random matrix model

We consider several limiting cases of the joint probability distribution for a random matrix ensemble with an additional interaction term controlled by an exponent γ (called the γ ensembles). The effective potential, which is essentially the single-particle confining potential for an equivalent ensemble with γ=1 (called the Muttalib-Borodin ensemble), is a crucial quantity defined in solution to the Riemann-Hilbert problem associated with the γ ensembles. It enables us to numerically compute the eigenvalue density of γ ensembles for all γ>0. We show that one important effect of the two-particle interaction parameter γ is to generate or enhance the nonmonotonicity in the effective single-particle potential. For suitable choices of the initial single-particle potentials, reducing γ can lead to a large nonmonotonicity in the effective potential, which in turn leads to significant changes in the density of eigenvalues. For a disordered conductor, this corresponds to a systematic decrease in the conductance with increasing disorder. This suggests that appropriate models of γ ensembles can be used as a possible framework to study the effects of disorder on the distribution of conductances.