67,944 research outputs found
Uniform Polynomial Equations Providing Higher-order Multi-dimensional Models in Lattice Boltzmann Theory
We present a set of polynomial equations that provides models of the lattice
Boltzmann theory for any required level of accuracy and for any dimensional
space in a general form. We explicitly derive two- and three-dimensional models
applicable to describe thermal compressible flows of the level of the
Navier-Stokes equations
Fragility, Stokes-Einstein violation, and correlated local excitations in a coarse-grained model of an ionic liquid
Dynamics of a coarse-grained model for the room-temperature ionic liquid,
1-ethyl-3-methylimidazolium hexafluorophosphate, couched in the united-atom
site representation are studied via molecular dynamics simulations. The
dynamically heterogeneous behavior of the model resembles that of fragile
supercooled liquids. At or close to room temperature, the model ionic liquid
exhibits slow dynamics, characterized by nonexponential structural relaxation
and subdiffusive behavior. The structural relaxation time, closely related to
the viscosity, shows a super-Arrhenius behavior. Local excitations, defined as
displacement of an ion exceeding a threshold distance, are found to be mainly
responsible for structural relaxation in the alternating structure of cations
and anions. As the temperature is lowered, excitations become progressively
more correlated. This results in the decoupling of exchange and persistence
times, reflecting a violation of the Stokes-Einstein relation.Comment: Published on the Phys. Chem. Chem. Phys. websit
Dirac Coupled-channel Analyses of Polarized Proton Scatterings to the 2 Gamma Vibrational Band in Mg and Mg
Dirac coupled channel calculations are performed phenomenologically for the
high-lying excited states that belong to the 2 gamma vibrational band at
the 800-MeV polarized proton inelastic scatterings from the s-d shell nuclei,
Mg and Mg. Optical potential model is used and scalar and
time-like vector potentials are considered as direct potentials. First-order
vibrational collective models are used to obtain the transition optical
potentials in order to accommodate the high-lying excited vibrational
collective states. The complicated Dirac coupled channel equations are solved
phenomenologically to reproduce the differential cross section and analyzing
power data by varying the optical potential and deformation parameters.
It is found that the relativistic Dirac coupled channel calculation could
describe the high-lying excited states of the 2 gamma vibrational band at
the 800-MeV polarized proton inelastic scatterings from s-d shell nuclei
Mg and Mg reasonably well, showing better agreement with the
experimental data compared to the results obtained from the nonrelativistic
calculations. Calculated deformation parameters for the excited states are
analyzed and compared with those of nonrelativistic calculations.Comment: 13pages, 6 figures. arXiv admin note: text overlap with
arXiv:1501.00650, arXiv:1407.5441, arXiv:1511.0172
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