145,134 research outputs found
Effect of distribution of stickers along backbone on temperature-dependent structural properties in associative polymer solutions
Effect of distribution of stickers along the backbone on structural
properties in associating polymer solutions is studied using self-consistent
field lattice model. Only two inhomogeneous morphologies, i.e.,
microfluctuation homogenous (MFH) and micelle morphologies, are observed. If
the system is cooled, the solvent content within the aggregates decreases. When
the spacing of stickers along the backbone is increased the
temperature-dependent range of aggregation in MFH morphology and half-width of
specific heat peak for homogenous solutions-MFH transition increase, and the
symmetry of the peak decreases. However, with increasing spacing of stickers,
the above three corresponding quantities related to micelles behave
differently. It is demonstrated that the broad nature of the observed
transitions can be ascribed to the structural changes which accompany the
replacement of solvents in aggregates by polymer, which is consistent with the
experimental conclusion. It is found that different effect of spacing of
stickers on the two transitions can be interpreted in terms of intrachain and
interchain associations.Comment: 10 pages, 4 figures. arXiv admin note: text overlap with
arXiv:1202.459
SU(4) Theory for Spin Systems with Orbital Degeneracy
The isotropic limit of spin systems with orbital degeneracy is shown to have
global SU(4) symmetry. On many 2D lattices, the ground state does not posses
long range order, which may explain the observed spin liquid properties of
. In the SU(4) Neel ordered state, spin-spin correlations can be
antiferromagneitc between two neighboring sites with parallel magnetic moments.Comment: 11 pages, 2 figures. submitted to PR
Statistical nature of cluster emission in nuclear liquid-vapour phase coexistence
The emission of nuclear clusters is investigated within the framework of
isospin dependent lattice gas model and classical molecular dynamics model. It
is found that the emission of individual cluster which is heavier than proton
is almost Poissonian except near the transition temperature at which the system
is leaving the liquid-vapor phase coexistence and the thermal scaling is
observed by the linear Arrhenius plots which is made from the average
multiplicity of each cluster versus the inverse of temperature in the liquid
vapor phase coexistence. The slopes of the Arrhenius plots, {\it i.e.} the
"emission barriers", are extracted as a function of the mass or charge number
and fitted by the formula embodied with the contributions of the surface energy
and Coulomb interaction. The good agreements are obtained in comparison with
the data for low energy conditional barriers. In addition, the possible
influences of the source size, Coulomb interaction and "freeze-out" density and
related physical implications are discussed
Dynamics aspect of subbarrier fusion reaction in light heavy ion systems
Subbarrier fusion of the 7Li + 12C reaction is studied using an
antisymmetrized molecular dynamics model (AMD) with an after burner, GEMINI. In
AMD, 7Li shows an \alpha + t structure at its ground state and it is
significantly deformed. Simulations are made near the Coulomb barrier energies,
i.e., E_{cm} = 3 - 8 MeV. The total fusion cross section of the AMD + GEMINI
calculations as a function of incident energy is compared to the experimental
results and both are in good agreement at E_{cm} > 3 MeV. The cross section for
the different residue channels of the AMD + GEMINI at E_{cm} = 5 MeV is also
compared to the experimental results.Comment: Talk given by Meirong Huang at the 11th International Conference on
Nucleus-Nucleus Collisions (NN2012), San Antonio, Texas, USA, May 27-June 1,
2012. To appear in the NN2012 Proceedings in Journal of Physics: Conference
Series (JPCS
Systematic studies of binding energy dependence of neutron - proton momentum correlation function
Hanbury Brown-Twiss (HBT) results of the neutron-proton correlation function
have been systematically investigated for a series nuclear reactions with light
projectiles with help of Isospin-Dependent Quantum Molecular Dynamics model.
The relationship between the binding energy per nucleon of the projectiles and
the strength of the neutron-proton HBT at small relative momentum has been
obtained. Results show that neutron-proton HBT results are sensitive to the
binding energy per nucleon.Comment: 10 pages, 5 figures; accepted by Journal of Physics G: Nuclear and
Particle Physic
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