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Silicon carbide (SiC) is a candidate structural material for fission and fusion reactors as well as an important wide band-gap semiconductor for electronic devices. Using first-principles calculations, we systemically investigate the energetics and stability of helium (He) atoms and intrinsic point defects inside single-crystalline 3C-SiC. We find that the formation energy of interstitial He is lower than those of point defects. Inside 3C-SiC, the He-C interaction is stronger than He-Si. Hence, the interstitial He atom in the Si tetrahedral site has a stronger interaction with the six C atoms in the second nearest neighbor than the four nearest neighboring Si atoms. For interstitial He atoms, the equilibrium He-He distance is about 1.81 Å with a weak attraction of 0.09 eV. According to the binding energies of Hen (n = 2–4) clusters, He interstitials can form He bubbles without involving other types of structural defects. Moreover, a Si (C) monovacancy can accommodate up to 11 (9) He atoms. The Hen clusters trapped in the Si or C monovacancy induce large internal pressure in the order of magnitude of GPa and thus facilitate the creation of a new vacancy at the nearby lattice site. [ABSTRACT FROM AUTHOR]

We systematically studied the validity and transferability of the force-matching algorithm for computing effective pair potentials in a system of dendritic polymers, i.e., a particular class of ultrasoft colloids. We focused on amphiphilic dendrimers, macromolecules which can aggregate into clusters of overlapping particles to minimize the contact area with the surrounding implicit solvent. Simulations were performed for both the monomeric and coarse-grained models in the liquid phase at densities ranging from infinite dilution up to values close to the freezing point. The effective pair potentials for the coarse-grained simulations were computed from the monomeric simulations both in the zero-density limit (Φeff) and at each investigated finite density (Φeff0) . Conducting the coarsegrained simulations with Φeff0) eff at higher densities is not appropriate as they failed at reproducing the structural properties of the monomeric simulations. In contrast, we found excellent agreement between the spatial dendrimer distributions obtained from the coarse-grained simulations with Φeff and the microscopically detailed simulations at low densities, where the macromolecules were distributed homogeneously in the system. However, the reliability of the coarse-grained simulations deteriorated significantly as the density was increased further and the cluster occupation became more polydisperse. Under these conditions, the effective pair potential of the coarse-grained model can no longer be computed by averaging over the whole system, but the local density needs to be taken into account instead. [ABSTRACT FROM AUTHOR]

We investigate the effective interaction between two randomly charged but otherwise net-neutral, planar dielectric slabs immersed in an asymmetric Coulomb fluid containing a mixture of mobile monovalent and multivalent ions. The presence of charge disorder on the apposed bounding surfaces of the slabs leads to substantial qualitative changes in the way they interact, as compared with the standard picture provided by the van der Waals and image-induced, ion-depletion interactions. While, the latter predict purely attractive interactions between strictly neutral slabs, we show that the combined effects from surface charge disorder, image depletion, Debye (or salt) screening, and also, in particular, their coupling with multivalent ions, give rise to a more diverse behavior for the effective interaction between net-neutral slabs at nano-scale separations. Disorder effects show large variation depending on the properly quantified strength of disorder, leading either to non-monotonic effective interaction with both repulsive and attractive branches when the surface charges are weakly disordered (small disorder variance) or to a dominating attractive interaction that is larger both in its range and magnitude than what is predicted from the van der Waals and image-induced, ion-depletion interactions, when the surfaces are strongly disordered (large disorder variance). [ABSTRACT FROM AUTHOR]

We study the phase behavior of colloidal suspensions the solvents of which are considered to be binary liquid mixtures undergoing phase segregation. We focus on the thermodynamic region close to the critical point of the accompanying miscibility gap. There, due to the colloidal particles acting as cavities in the critical medium, the spatial confinements of the critical fluctuations of the corresponding order parameter result in the effective, so-called critical Casimir forces between the colloids. Employing an approach in terms of effective, one-component colloidal systems, we explore the possibility of phase coexistence between two phases of colloidal suspensions, one being rich and the other being poor in colloidal particles. The reliability of this effective approach is discussed. [ABSTRACT FROM AUTHOR]

We explore in detail the structural, mechanical, and thermodynamic properties of a coarse-grained model of DNA similar to that recently introduced in a study of DNA nanotweezers [T. E. Ouldridge, A. A. Louis, and J. P. K. Doye, Phys. Rev. Lett. 134, 178101 (2010)]. Effective interactions are used to represent chain connectivity, excluded volume, base stacking, and hydrogen bonding, naturally reproducing a range of DNA behavior. The model incorporates the specificity of Watson-Crick base pairing, but otherwise neglects sequence dependence of interaction strengths, resulting in an 'average base' description of DNA. We quantify the relation to experiment of the thermodynamics of single-stranded stacking, duplex hybridization, and hairpin formation, as well as structural properties such as the persistence length of single strands and duplexes, and the elastic torsional and stretching moduli of double helices. We also explore the model's representation of more complex motifs involving dangling ends, bulged bases and internal loops, and the effect of stacking and fraying on the thermodynamics of the duplex formation transition. [ABSTRACT FROM AUTHOR]

We study the effective interaction between differently charged polyelectrolyte-colloid complexes in electrolyte solutions via Monte Carlo simulations. These complexes are formed when short and flexible polyelectrolyte chains adsorb onto oppositely charged colloidal spheres, dispersed in an electrolyte solution. In our simulations the bending energy between adjacent monomers is small compared to the electrostatic energy, and the chains, once adsorbed, do not exchange with the solution, although they rearrange on the particles surface to accommodate further adsorbing chains or due to the electrostatic interaction with neighbor complexes. Rather unexpectedly, when two interacting particles approach each other, the rearrangement of the surface charge distribution invariably produces antiparallel dipolar doublets that invert their orientation at the isoelectric point. These findings clearly rule out a contribution of dipole-dipole interactions to the observed attractive interaction between the complexes, pointing out that such suspensions cannot be considered dipolar fluids. On varying the ionic strength of the electrolyte, we find that a screening length κ-1, short compared with the size of the colloidal particles, is required in order to observe the attraction between like-charged complexes due to the nonuniform distribution of the electric charge on their surface (“patch attraction”). On the other hand, by changing the polyelectrolyte/particle charge ratio ξs, the interaction between like-charged polyelectrolyte-decorated particles, at short separations, evolves from purely repulsive to strongly attractive. Hence, the effective interaction between the complexes is characterized by a potential barrier, whose height depends on the net charge and on the nonuniformity of their surface charge distribution. [ABSTRACT FROM AUTHOR]

General expressions for two-center electrostatic potential correlations and its use to determine (i) the effective interaction between simple ions in a dipolar solvent and (ii) the dielectric permittivity of the solvent are proposed. Such two-center potential correlations were determined from Monte Carlo simulations of spherically confined dipolar particles embedded in a dielectric medium described by using an image charge approximation. The deduced dielectric permittivities increased with increasing dipolar moment, and at large dipole moments the effective interaction displayed an attractive first minimum. [ABSTRACT FROM AUTHOR]

The problem of a biexciton confined in parabolic GaAs quantum-well wires in the presence of a perpendicular magnetic field is discussed. We apply an analytical one-dimensional formula for the effective interaction potential between the confined charge carriers to study the binding energies of a biexciton, which results in a numerical “exactly” solvable model. The ratio of the binding energy of a biexciton to that of an exciton for a range of confinement lengths (l

Using integral equation theory of liquids to a binary mixed fluid lipid membrane, the authors study the membrane-mediated interactions between binding macroions and the redistribution of neutral and charged lipids due to the macroions. The authors find that when the concentration of binding macroions is infinitely dilute, the main contribution to the attractive potential between macroions is the line tension between neutral and charged lipids of the membrane. As the relative concentration of charged lipids is increased, the authors observe a repulsive-attractive-repulsive potential transition due to the competition between the line tension of mixed lipids and screened electrostatic macroion-macroion interactions. For the finite concentration of macroions, the main feature of the attraction is similar to the infinite-diluted case. However, the corresponding line tension of binary lipids under single macroion is lowered with the formation of multicomplexes by the charged lipids and the macroions, and the maximum of attractive potential will shift toward the higher values of charged lipid concentration. [ABSTRACT FROM AUTHOR]

First-principles calculations are performed to study the interaction of cluster Au32 with small molecules, such as CO, H2, and O2. The cagelike Au32(Ih) shows a higher chemical inertness than the amorphous Au32(C1) with respect to the interaction with small molecules CO, H2, and O2. H2 can only be physically adsorbed on Au32(Ih), while it can be dissociatively chemisorbed on Au32(C1). Although CO can be chemically adsorbed on Au32(Ih) and Au32(C1) with one electron transferred from Au32 to the antibonding π* orbit of CO, it is bound more strongly on Au32(C1) than on Au32(Ih). Spin polarized and spin nonpolarized calculations result almost identical ground state structures of Au32(Ih)–O2 and Au32(C1)–O2, in which O2 is dissociatively chemisorbed. [ABSTRACT FROM AUTHOR]

First-principles calculations are performed to study the interaction of cluster Au32 with small molecules, such as CO, H2, and O2. The cagelike Au32(Ih) shows a higher chemical inertness than the amorphous Au32(C1) with respect to the interaction with small molecules CO, H2, and O2. H2 can only be physically adsorbed on Au32(Ih), while it can be dissociatively chemisorbed on Au32(C1). Although CO can be chemically adsorbed on Au32(Ih) and Au32(C1) with one electron transferred from Au32 to the antibonding π* orbit of CO, it is bound more strongly on Au32(C1) than on Au32(Ih). Spin polarized and spin nonpolarized calculations result almost identical ground state structures of Au32(Ih)–O2 and Au32(C1)–O2, in which O2 is dissociatively chemisorbed. [ABSTRACT FROM AUTHOR]

We study the effective interactions among large hard spherical colloidal particles induced by small hard rodlike particles and compare them with those induced by small hard spherical particles to highlight the specific effects due to the anisotropic shape of the former. This is done by determining the effective pair potentials within the framework of the reference interaction site model approach. The rodlike particles are modeled as N nonoverlapping spherical units arranged in a straight line, so that their total length is N times their transversal diameter. These results are compared against those obtained in the Asakura-Oosawa limit. [ABSTRACT FROM AUTHOR]

Realistic interactions that operate in condensed matter systems can exhibit complicated many-particle characteristics. However, it is often useful to seek a more economical description using at most singlet and pair effective interactions that are density dependent, to take advantage of the theoretical and computational simplifications that result. This paper analyzes the statistical mechanical formalism required to describe thermal equilibrium in that kind of approach. Two distinct interpretations are available for the role of density dependence. Either one can be treated with internal consistency, but generally they lead to differing thermodynamic predictions. One regards the density dependence of effective interactions as merely a passive index for the state at which the optimal choice of those effective interactions was determined (Case I). The other treats the density as an active variable on the same footing as particle coordinates (Case II). Virial pressure and isothermal compressibility expressions in terms of particle distribution functions are displayed for both cases. Under special circumstances it is possible for the two interpretations to yield the same pressure isotherms; the conditions producing this coincidental concordancy have been explored by means of density expansions. [ABSTRACT FROM AUTHOR]

C–H–O interaction of acetone and deuterium oxide has been probed by high pressure. High-pressure study provides the first experimental evidence for the enhancement of hydrophobic hydration of acetone as its aqueous solution was compressed to high-pressure ices. Based on the results, we conclude that the C–H–O interaction may be a distinct possibility to understand the origin of the spectral feature located at ∼2950 cm-1, being sensitive to concentration and pressure dependence. Ab initio calculation results, forecasting the frequency red shift of the C–H stretching vibration as C–H–O is interacted via hydrogen bonding, are discussed. This study demonstrates that high pressure can be used as a valuable means of triggering and investigating C–H–O hydrogen-bonding interaction. © 2001 American Institute of Physics. [ABSTRACT FROM AUTHOR]

The lattice cluster theory with structured monomers is used to analyze the small angle neutron scattering experiments of Russell et al. on the polystyrene–b-poly(methyl methacrylate) diblock copolymer system in order to gain insight into the observed large entropic contribution to the effective interaction parameter χeff. Predictions are made of the composition and molecular weight dependence of χeff and of the pressure and composition dependence of the microphase transition temperature to the bcc microphase. General predictions are also compared with experimental data for poly(ethylenepropylene)–poly(ethylethylene) diblock copolymers. [ABSTRACT FROM AUTHOR]

A pseudospectral formulation of the full configuration interaction method is presented in this paper. This represents the first application of the pseudospectral approximation to configuration interaction expansions. It is shown that a formal scaling advantage of n, the number of molecular orbital basis functions, is achieved. The spectral and pseudospectral total energies obtained for a series of first-row atoms and ions are compared. The relative operation counts of the spectral and pseudospectral methods are also discussed in this paper. Finally, two hybrid spectral/pseudospectral approximations that vastly improve the accuracy of the pseudospectral total energies are presented. [ABSTRACT FROM AUTHOR]

The effective interaction energy of two test particles immersed in a molecular fluid of finite volume is defined and expressed in terms of the molecular pair correlation function. The specific problem of electric multipoles immersed in a fluid of polar nonpolarizable molecules filling a spherical volume is then analyzed in detail. The long-range part of the effective interaction of the test multipoles is obtained to leading order in 1/V. A comparison is made with similar results obtained in the case of infinite volume. [ABSTRACT FROM AUTHOR]

Coexistence in schools inevitably carries a higher risk of conflicts among peers. This fact can be detrimental to the well-being and academic achievement of the students. In many developed countries, about 90% of the pupils in compulsory secondary education report witnessing assaults among peers. In this regard, recognizing, controlling and managing emotions is key to ensure a healthy and effective interaction with others. Negative emotions, such as anger, can trigger conflicts or even episodes of violence if not regulated properly. Interactive tools, such as specialized software's, have shown high rates of efficacy for the training of different kinds of competences like the regulation of emotions. The aim of the present work is to describe the Happy Emotional Education Program and its effects over a sample of secondary school students. This software focuses in the training of emotional competences of the students with the objective of solving conflicts in a more assertive way. The design employed in the present work was a quasiexperimental design with pretest and posttest with a control group. Results show that Happy Emotional Education Program contributes to the management of emotions and the absence of negative affect or anxiety in a significant way. Additionally, the constant use of this interactive tool enhances motivation and the learning process of students. Results also indicate the importance of assessing the effects of the program in the long term. This would enable researchers to further assess the effects of the program over those emotional competences that are more resistant to change given its stable nature. [ABSTRACT FROM AUTHOR]

The effective interaction between the itinerant spin degrees of freedom in the paramagnetic phases of hole-doped quantum Heisenberg antiferromagnets is investigated theoretically, based on the single-band t-J model on 1D lattice, at zero temperature. The effective spin-spin interaction for this model in the strong correlation limit is studied in terms of the generalized spin stiffness constant as a function of doping concentration. The plot of this generalized spin stiffness constant against doping shows a very high value of stiffness in the vicinity of zero doping and a very sharp fall with increase in doping concentration, signifying the rapid decay of original coupling of semi-localized spins in the system. Quite interestingly, this plot also shows a maximum occurring at a finite value of doping, which strongly suggests the tendency of the itinerant spins to couple again in the unconventional paramagnetic phase. As the doping is further increased, this new coupling is also suppressed and the spin response becomes analogous to almost Pauli-like. The last two predictions of ours are quite novel and may be directly tested by independent experiments and computational techniques in future. Our results in general receive good support from other theoretical works and experimental results extracted from the chains of YBa2Cu3O6+x. [ABSTRACT FROM AUTHOR]

The Fock-Tani formalism is a first-principles method to obtain effective interactions from microscopic Hamiltonians. Originally derived for meson-meson or baryon-baryon scattering, we present in this paper a brief introduction to the Fock-Tani formalism and formulate the meson-baryon potential, with the scattering and annihilation parts explicitly taken into account, and the corresponding diagrams. Finally, we present the differential and total cross-section calculations that will be used, in the near future, in the description of kaon-nucleon interactions. [ABSTRACT FROM AUTHOR]

The fusion dynamics of reaction has been studied using different theoretical approaches like energy-dependent Woods-Saxon potential (EDWSP) model, coupled channel formulation and Wong approach. At sub-barrier energies, the anomalously large enhancement of the fusion cross-section signifies the importance of barrier modification effects for the adequate addressal of experimental data. The EDWSP model, wherein barrier modification effects are introduced via the energy-dependent diffuseness parameter, is used to examine the sub-barrier fusion anomalies. In the framework of coupled channel model, the impacts of collective excitations and/or static deformations of colliding partners are incorporated in the fusion dynamics. In Wong formula, the role of different Skyrme forces such as SIII, KDE0v1, SkT1, SSk, GSkI is analyzed to address the observed fusion enhancement around the Coulomb barrier. Among these, GSkI and SSk forces seem more appropriate for the addressal of fusion dynamics at sub-barrier energies while SIII, SkT1 and KDE0v1 forces give relatively better results at the above barrier region. The SSk (GSkI) force at higher energies overestimate the experimental data and hence treated with the -summed Wong approach. The effect of deformations and optimum orientations is duly incorporated in the calculation and hence gives better description to the observed data. In addition, the fusion cross-sections are predicted over extreme energies using EDWSP and -summed Wong approach. It is worth mentioning here that the different theoretical approaches (EDWSP, coupled channel and Wong) induce similar kinds of barrier lowering effects, henceforth, they reasonably describe the sub-barrier fusion data of reaction. [ABSTRACT FROM AUTHOR]

We show that couplings of the goldstino field, appearing when global supersymmetry is broken, can always be described in superspace by means of a nilpotent chiral superfield X, satisfying X = 0. This applies to both F-term and D-term supersymmetry breaking, even when the supersymmetry breaking model admits a linear description. [ABSTRACT FROM AUTHOR]

Ensuring the safety and streamline in road traffic are very important aims, with regard to the nowadays people mobility level. Road infrastructure is an essential element that can meet these requirements. Thus, it is proposed to develop an effective model of intersection by using CAD software tools. This type of intersection can be successfully used on almost any category of roads, increasing road traffic safety, reducing passing times through the intersection and in the same time, reducing conflict points and increase the intersection capacity. [ABSTRACT FROM AUTHOR]

Research Findings: This study investigated the relationship between features of the classroom environment and misalignment between teacher and observer ratings of preschoolers’ classroom engagement and the extent to which years of teaching experience moderated this relationship. In a sample of 116 preschoolers and 21 teachers in 29 classrooms, classroom engagement was assessed using teacher report and independent direct observation. Classroom-level predictors included severity of challenging behaviors, child:adult ratio, and the percentage of students from economically disadvantaged backgrounds. Lower misalignment was noted on ratings of negative engagement than positive engagement. Multilevel regression analyses revealed that misalignment was largely independent of variation in classroom factors, except for a consistent interaction between years of teaching experience and child:adult ratio. Specifically, observers’ ratings were less misaligned with novice teachers’ ratings than veterans’ in classrooms with a high child:adult ratio, whereas the opposite trend was found in classrooms with low child:adult ratios.Practice or Policy: Findings are discussed in light of current best practice calling for a multidisciplinary approach when conducting assessments on young children, despite little guidance on how to handle misalignment between raters when determining service eligibility and developing effective interventions. [ABSTRACT FROM AUTHOR]

In this paper, we investigate interaction of primary cascades with grain boundaries (GBs) in α-Zr using the atomistic-scale simulations, and intend to study the influence of different GB structures on production and evolution of defects on picosecond timescale. We observe that, contrary to the previous results in cubic metals, GBs in α-Zr are not necessarily biased toward interstitials, and can preferentially absorb vacancies. Further, in terms of energetic and kinetic behavior, we find that GBs act as defect sinks due to the substantial reduction of defect formation energies and migration barriers in close vicinity of the GB center, with either a preference toward interstitials or vacancies which depends on the atomic structure of the boundaries. Finally, using continuous ion bombardment, we investigate the stability of GBs in sever irradiation environment. The results indicate that the sink strength and efficiency of boundaries varies with increasing accumulated defects in GB region. [ABSTRACT FROM AUTHOR]

In the framework of vector model of spin, we discuss the problem of a covariant formalism [35] concerning the discrepancy between relativistic and Pauli Hamiltonians. We show how the spin-induced non-commutativity of a position accounts the discrepancy on the classical level, without appeal to the Dirac equation and Foldy–Wouthuysen transformation. [ABSTRACT FROM AUTHOR]

We consider the possibility of new physics giving rise to effective interactions of the form e + e − H f f ¯ , where f represents a charged lepton ℓ or a (light) quark q , and H the recently discovered Higgs boson. Such vertices would give contributions beyond the standard model to the Higgs production processes e + e − → H ℓ + ℓ − and e + e − → H q q ¯ at a future e + e − collider. We write the most general form for these vertices allowed by Lorentz symmetry. Assuming that such interactions contribute in addition to the standard model production processes, where the final-state fermion pair comes from the decay of the Z boson, we obtain the differential cross section for the processes e + e − → H ℓ + ℓ − and e + e − → H q q ¯ to linear order in the effective interactions. We propose several observables with differing CP and T properties which, if measured, can be used to constrain the couplings occurring in interaction vertices. We derive possible limits on these couplings that may be obtained at a collider with centre-of-mass energy of 500 GeV and an integrated luminosity of 500 fb − 1 . We also carry out the analysis assuming that both the electron and positron beams can be longitudinally polarized, and find that the sensitivity to the couplings can be improved by a factor of 2–4 by a specific choice of the signs of the polarizations of both the electron and positron beams for the same integrated luminosity. [ABSTRACT FROM AUTHOR]

An interaction model considering the local stress on a particle surface is developed based on a volume averaging technique. With a scope to apply to turbulence modulation caused by particles of diameter comparable to the Kolmogorov length scale, grid width for resolving vortical structures outside the boundary layer of the particles is set to be close to the particle diameter. The interaction force in the volume-averaged momentum equation is modelled based on analytical solutions of two fundamental flows. For the uniform flow case, the nonlinear effect of the first-order term in a series expansion with respect to the particle Reynolds number is found to be essential for the anisotropic Eulerian distribution of the interaction force. For the shear flow case, the anisotropic distribution of the interaction force is also essential, and it is modelled based on the Stokes’s solution. Considering that the length scale of the averaging volume is determined to be comparable to the grid width and the particle diameter, the residual stress, which originates from the volume averaging of the nonlinear term in the momentum equation, is also modelled based on an undisturbed linear shear flow. According to the test simulation using the interaction force and residual stress models of the fundamental flows, the anisotropic interaction force model essentially improves the representation of the flow field and the mechanical work, and the effect of the residual stress is found to be reasonably reproduced by the present model. [ABSTRACT FROM AUTHOR]

We present a unified description of effective interaction theories in both algebraic and graphic representations. In our previous work, we have presented the Rayleigh–Schrödinger and Bloch perturbation theories in a unified fashion by introducing the main frame expansion of the effective interaction. In this work, we start also from the main frame expansion, and present various nonperturbative theories in a coherent manner, which include generalizations of the Brandow, Brillouin–Wigner, and Bloch–Horowitz theories on the formal side, and the extended Krenciglowa–Kuo and the extended Lee–Suzuki methods on the practical side. We thus establish a coherent and comprehensive description of both perturbative and nonperturbative theories on the basis of the main frame expansion. [ABSTRACT FROM AUTHOR]

A recently developed three-Dimensional (3D) approach, without Partial-Wave (PW) decomposition is considered to investigate solutions of Faddeev-Yakubovsky (F-Y) integral equations in momentum space representation. The F-Y formulation for six-nucleon bound-state problem leads to five coupled equations in terms of five independent structures, which can be reduced to two coupled ones for considering the effective interactions of the two loosely bound nucleons with respect to the -core nucleus. In order to study, the effective structure of six-nucleon bound-state in 3D representation, the coupled equations are represented in momentum space as a two coupled 3D integral equations. This is the first step to approach the calculations, of six-nucleon bound-state problem in 3D approach. In our calculations, we considered simple potential models, namely spin-independent two-body (2B) interactions. Our numerical results are fair compatible with results of other methods. [ABSTRACT FROM AUTHOR]

An unconventional type of the Mott's insulators where the gap in the spectrum of single-particle excitations is associated with repulsive effective interactions between quasiparticles is shown to exist in strongly correlated electron systems of solids that possess flat bands. The occurrence of this gap is demonstrated to be the consequence of violation of particle-hole symmetry, inherent in such systems. The results obtained are applied to elucidate the Fermi arc structure observed at temperatures up to 100 K in angle-resolved photoemission spectra of the compound SrIrO, not showing superconductivity down to low T. [ABSTRACT FROM AUTHOR]

We show that it is possible to model two-body resonant interactions at low energy with a class of finite-range potentials based on the methods of Jost and Kohn. These potentials are expressed in terms of the effective range and the -wave scattering length . We derive continuum solutions of these potentials. By writing , where the sign refers to positive(negative) scattering length, is of the form of Pöschl-Teller potential and is expressed as a power series of the small parameter when is large, we derive Green's function of . Using the Green's function, solutions of for can be obtained numerically by treating as a perturbation. We describe the threshold behavior of scattering phase shift for . This study may be important for developing a better understanding of physics of strongly interacting ultracold atomic gases with tunable interactions. [ABSTRACT FROM AUTHOR]

We present a unified description of the Bloch and Rayleigh–Schrödinger perturbation theories of the effective interaction in both algebraic and graphic representations. [ABSTRACT FROM AUTHOR]

Momentum and density dependence of single-nucleon potential u ( k, ρ, β) is analyzed using a density dependent finite range effective interaction of the Yukawa form. Depending on the choice of the strength parameters of exchange interaction, two different trends of the momentum dependence of nuclear symmetry potential are noticed which lead to two opposite types of neutron and proton effective mass splitting. The 2nd-order and 4th-order symmetry energy of isospin asymmetric nuclear matter are expressed analytically in terms of the single-nucleon potential. Two distinct behavior of the density dependence of 2nd-order and 4th-order symmetry energy are observed depending on neutron and proton effective mass splitting. It is also found that the 4th-order symmetry energy has a significant contribution towards the proton fraction of β-stable npeμ matter at high densities. [ABSTRACT FROM AUTHOR]

We present molecular dynamics (MD) calculations of shear viscosity for asymmetric mixed plasma for thermodynamic conditions relevant to astrophysical and inertial confinement fusion plasmas. Specifically, we consider mixtures of deuterium and argon at temperatures of 100-500 eV and a number density of 1025 ions/cc. The motion of 30 000-120 000 ions is simulated in which the ions interact via the Yukawa (screened Coulomb) potential. The electric field of the electrons is included in this effective interaction; the electrons are not simulated explicitly. Shear viscosity is calculated using the Green-Kubo approach with an integral of the shear stress autocorrelation function, a quantity calculated in the equilibrium MD simulations. We systematically study different mixtures through a series of simulations with increasing fraction of the minority high-Z element (Ar) in the D-Ar plasma mixture. In the more weakly coupled plasmas, at 500 eV and low Ar fractions, results from MD compare very well with Chapman-Enskog kinetic results. In the more strongly coupled plasmas, the kinetic theory does not agree well with the MD results. We develop a simple model that interpolates between classical kinetic theories at weak coupling and the Murillo Yukawa viscosity model at higher coupling. This hybrid kinetics-MD viscosity model agrees well with the MD results over the conditions simulated, ranging from moderately weakly coupled to moderately strongly coupled asymmetric plasma mixtures. [ABSTRACT FROM AUTHOR]

The odd–odd nucleus 30 Na is studied via a one-proton, one-proton–one-neutron and one-neutron removal reaction using an intermediate-energy 31 Mg, 32 Mg and 31 Na radioactive ion beam, respectively. Combining high-resolution γ -ray spectroscopy with the selectivity of the three reaction mechanisms, we are able to distinguish multiple particle–hole configurations. Negative-parity states in 30 Na are observed for the first time, providing an important measure of the excitation of the 1p1h/3p3h configuration and hence the sd – pf shell gap. The extracted band structures and level energies serve as invaluable input for the theoretical refinement of the effective interactions used in this region. [ABSTRACT FROM AUTHOR]

Recent observation of the 6+ seniority isomers and measurements of the B(E2) values in the 134-138Sn isotopes lying close to the neutron drip line have raised some questions about the validity of the currently used effective interactions in the neutron-rich region. Simpson et al. [Phys. Rev. Lett. 113, 132502 (2014)] had to modify the diagonal and nondiagonal νf7/2² two-body matrix elements of the Vlk interaction by ~150 keV in their shell model calculations in order to explain the data of 136Sn. In contrast, we are able to explain the observed energy levels and the B(E2) values after marginal reduction of the same set of matrix elements by 25 keV in the RCDB (renormalized CD-Bonn) interaction. The observed mismatch in reproducing the data of 136Sn is due to the seniority mixing. Further, we do not find it necessary to consider the core excitations, and the RCDB interaction seems better suited to explain the data beyond N = 82 magic number. [ABSTRACT FROM AUTHOR]

Passive particles exhibit unique properties when immersed in an active bath of self-propelling entities. In particular, an effective attraction can appear between particles that repel each other when in a passive solution. Here we numerically study the effect of hydrodynamics on an active-passive hybrid system, where we observe qualitative differences as compared to simulations with excluded volume effects alone. The results shed light on an existing discrepancy in pair lifetimes between simulation and experiment, due to the hydrodynamically enhanced stability of coupled passive particles. [ABSTRACT FROM AUTHOR]