The Experts below are selected from a list of 5784 Experts worldwide ranked by ideXlab platform
G V Shlyapnikov - One of the best experts on this subject based on the ideXlab platform.
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bose einstein condensation in trapped dipolar gases
Physical Review Letters, 2000Co-Authors: L Santos, G V Shlyapnikov, P Zoller, Maciej LewensteinAbstract:We discuss Bose-Einstein condensation in a trapped gas of bosonic particles interacting dominantly via dipole-dipole forces. We find that in this case the mean-field Interparticle Interaction and, hence, the stability diagram are governed by the trapping geometry. Possible physical realizations include ultracold heteronuclear molecules, or atoms with laser induced electric dipole moments.
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collapse and bose einstein condensation in a trapped bose gas with negative scattering length
Physical Review Letters, 1998Co-Authors: Yu Kagan, G V Shlyapnikov, A E MuryshevAbstract:Evolution and collapse of a trapped Bose condensate with negative scattering length are predetermined by 3-body recombination of Bose-condensed atoms and by feeding of the condensate from the nonequilibrium thermal cloud. The collapse, starting once the number of condensate atoms reaches the critical value, ceases and turns to expansion when the density becomes so high that the recombination losses dominate over attractive Interparticle Interaction. As a result, we obtain a sequence of collapses, each of them followed by dynamic oscillations of the condensate. In every collapse the 3-body recombination burns only a part of the Bose-condensed atoms.
Cao Yang - One of the best experts on this subject based on the ideXlab platform.
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bosons or fermions in 1d power potential trap with repulsive delta function Interaction
Chinese Physics Letters, 2010Co-Authors: M A Zhongqi, Cao YangAbstract:We study the ground state of a 1D many Boson or Fermion system with repulsive delta function Interparticle Interaction trapped in an external potential V(x) = |x|a/2 where a > 0.
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spinless bosons in a 1d harmonic trap with repulsive delta function Interparticle Interaction ii numerical solutions
Chinese Physics Letters, 2010Co-Authors: M A Zhongqi, Cao YangAbstract:Following the general theory developed in paper I [Chin. Phys. Lett. 26 (2009) 120506] we present here the numerical results for an N spinless boson system in a 1D harmonic trap with repulsive delta function Interparticle Interaction as N ? ?, with ?N/g = fixed.
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spinless bosons in a 1d harmonic trap with repulsive delta function Interparticle Interaction i general theory
Chinese Physics Letters, 2009Co-Authors: M A Zhongqi, Cao YangAbstract:In these two papers, we solve the N body 1D harmonically trapped spinless Boson problem with repulsive ? function Interaction in the limit N ? ?. The general theory is given in paper I and the numerical solutions will be given in paper II.
D V Berkov - One of the best experts on this subject based on the ideXlab platform.
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density of energy barriers in fine magnetic particle systems
IEEE International Magnetics Conference, 2002Co-Authors: D V BerkovAbstract:Using a numerical method based on the minimization of the Onsager-Machlup functional, we have studied the energy barrier distributions in systems of fine magnetic particles with the uniaxial anisotropy and the dipolar Interaction. In such systems, the interplay of the single particle anisotropy and the dipolar Interaction strength (particle concentration) determines whether the single-particle or collective remagnetization dominates the system behavior (including barrier heights). Our main conclusion is that the influence of the dipolar Interparticle Interaction on the energy barrier density /spl rho/(E) depends qualitatively on the single particle anisotropy. For low anisotropies /spl rho/(E) shifts toward higher barriers when increasing Interaction strength, whereby for moderate and high anisotropy values, the opposite shift takes place. We propose the explanation for this phenomenon.
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the langevin dynamics simulation of interacting fine magnetic particle systems
Journal of Magnetism and Magnetic Materials, 2001Co-Authors: D V Berkov, N L Gorn, Peter GörnertAbstract:Abstract Using Langevin dynamics simulations, we have calculated the AC-susceptibility χ = χ ′+ iχ ″ of disordered fine magnetic particle systems with the dipolar Interparticle Interaction. We have shown that the shift of the χ ″( T )-peak with increasing particle concentration depends qualitatively on the single-particle anisotropy and quantitatively on the precession damping.
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numerical calculation of the energy barrier distribution in disordered many particle systems the path integral method
Journal of Magnetism and Magnetic Materials, 1998Co-Authors: D V BerkovAbstract:Abstract We present a numerical method for the evaluation of the distribution of energy barriers between metastable states in many-particle systems with arbitrary Interparticle Interaction. The method is based on the search for the optimal path between the two given metastable states using the minimization of the corresponding action occurring in the Onsager–Machlup functional for the transition probability between these two states. Test results for a non-interacting system of magnetic particles and for a dipolar magnetic glass are reported.
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numerical simulations of quasistatic remagnetization processes in fine magnetic particle systems
Journal of Magnetism and Magnetic Materials, 1996Co-Authors: D V BerkovAbstract:Abstract Various numerical methods used for simulation of quasistatic remagnetization processes in interacting systems of fine single-domain magnetic particles are analyzed. Among them methods based on the sequential alignment of magnetic moments along the effective field are found to be the fastest, especially in the most interesting case of a small single particle anisotropy when cooperative remagnetization modes play a dominant role. Further it is shown, that the random field approximation (RFA) which is often used to take the Interparticle Interaction effects into account is valid for large particle anisotropies only. The distribution density of the Interaction field is found to transform from the Lorentzian to the Gaussian form with the increasing particle volume fraction. Finally hysteresis loops for a wide range of single-particle anisotropy values and particle concentration are calculated and the crossover from the single particle to the collective behavior with decreasing single particle anisotropy is investigated.
Jordi Boronat - One of the best experts on this subject based on the ideXlab platform.
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Universality of size-energy ratio in four-body systems
Scientific reports, 2019Co-Authors: Petar Stipanović, Leandra Vranješ Markić, Andrii Gudyma, Jordi BoronatAbstract:Universal relationship of scaled size and scaled energy, which was previously established for two- and three-body systems in their ground state, is examined for four-body systems, using Quantum Monte Carlo simulations. We study in detail the halo region, in which systems are extremely weakly bound. Strengthening the Interparticle Interaction we extend the exploration all the way to classical systems. Universal size-energy law is found for homogeneous tetramers in the case of Interaction potentials decaying predominantly as r−6. In the case of mixed tetramers, we also show under which conditions the universal line can approximately describe the size-energy ratio. The universal law can be used to extract ground-state energy from experimentally measurable structural characteristics, as well as for evaluation of theoretical Interaction models.
Chunyu Chen - One of the best experts on this subject based on the ideXlab platform.
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hierarchical self assembly of nanoparticles in polymer matrix and the nature of the Interparticle Interaction
Journal of Chemical Physics, 2015Co-Authors: Chunyu Chen, Hsinlung Chen, Takeji Hashimoto, Showan Chen, Yencheng LiAbstract:Using small angle X-ray scattering (SAXS), we elucidated the spatial organization of palladium (Pd) nanoparticles (NPs) in the polymer matrix of poly(2-vinylpyridine) (P2VP) and the nature of inter-nanoparticle Interactions, where the NPs were synthesized in the presence of P2VP by the reduction of palladium acetylacetonate (Pd(acac)2). The experimental SAXS profiles were analysed on the basis of a hierarchical structure model considering the following two types of Interparticle potential: (i) hard-core repulsion only (i.e., the hard-sphere Interaction) and (ii) hard-core repulsion together with an attractive potential well (i.e., the sticky hard-sphere Interaction). The corresponding theoretical scattering functions, which were used for analysing the experimental SAXS profiles, were obtained within the context of the Percus-Yevick closure and the Ornstein-Zernike equation in the fundamental liquid theory. The analyses revealed that existence of the attractive potential well is indispensable to account fo...
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hierarchical self assembly of nanoparticles in polymer matrix and the nature of the Interparticle Interaction
Journal of Chemical Physics, 2015Co-Authors: Yuchiao Lin, Chunyu Chen, Hsinlung Chen, Takeji Hashimoto, Showan ChenAbstract:Using small angle X-ray scattering (SAXS), we elucidated the spatial organization of palladium (Pd) nanoparticles (NPs) in the polymer matrix of poly(2-vinylpyridine) (P2VP) and the nature of inter-nanoparticle Interactions, where the NPs were synthesized in the presence of P2VP by the reduction of palladium acetylacetonate (Pd(acac)2). The experimental SAXS profiles were analysed on the basis of a hierarchical structure model considering the following two types of Interparticle potential: (i) hard-core repulsion only (i.e., the hard-sphere Interaction) and (ii) hard-core repulsion together with an attractive potential well (i.e., the sticky hard-sphere Interaction). The corresponding theoretical scattering functions, which were used for analysing the experimental SAXS profiles, were obtained within the context of the Percus-Yevick closure and the Ornstein-Zernike equation in the fundamental liquid theory. The analyses revealed that existence of the attractive potential well is indispensable to account for the experimental SAXS profiles. Moreover, the morphology of the hybrids was found to be characterized by a hierarchical structure with three levels, where about six primary NPs with the diameter of ca. 1.8 nm (level one) formed local clusters (level two), and these clusters aggregated to build up a large-scale mass-fractal structure (level three) with the fractal dimension of ca. 2.3. The scattering function developed here is of general use for quantitatively characterizing the morphological structures of polymer/NP hybrids and, in particular, for exploring the Interaction potential of the NPs on the basis of the fundamental liquid theory.
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reaction kinetics and formation mechanism of tio2 nanorods in solution an insight into oriented attachment
Journal of Physical Chemistry C, 2014Co-Authors: Chengsi Tsao, Chunyu Chen, Chihmin Chuang, Yuching Huang, Houchin Cha, Fanhsuan Hsu, Charnying ChenAbstract:The reaction kinetics and formation mechanism of oriented attachment for shaped nanoparticles in solution are not well-understood. We present the reaction kinetics and formation mechanism of organic-capped anatase TiO2 nanorods in solution as a case study for the oriented attachment process using small-angle X-ray scattering (SAXS) and transmission electronic microscopy. The SAXS analysis qualitatively and quantitatively provides in-depth understanding of the mechanism, including the structural evolution, Interparticle Interaction, and spatial orientation of nanoparticles developed from nanodots to nanorods during the nucleation, isotropic, and anisotropic growth steps. The present study demonstrates the growth details of oriented attachment of nanoparticles in solution. An ordered lamellar structure in the solution is constructed by the balance of Interaction forces among surface ligands, functional groups, and solvent molecules serving as a natural template. The template allows the alignment of spherica...
