3,728 research outputs found
Reweighting for Nonequilibrium Markov Processes Using Sequential Importance Sampling Methods
We present a generic reweighting method for nonequilibrium Markov processes.
With nonequilibrium Monte Carlo simulations at a single temperature, one
calculates the time evolution of physical quantities at different temperatures,
which greatly saves the computational time. Using the dynamical finite-size
scaling analysis for the nonequilibrium relaxation, one can study the dynamical
properties of phase transitions together with the equilibrium ones. We
demonstrate the procedure for the Ising model with the Metropolis algorithm,
but the present formalism is general and can be applied to a variety of systems
as well as with different Monte Carlo update schemes.Comment: accepted for publication in Phys. Rev. E (Rapid Communications
Important role of the spin-orbit interaction in forming the 1/2^+ orbital structure in Be isotopes
The structure of the second 0^+ state of ^{10}Be is investigated using a
microscopic model based on the molecular-orbit (MO) model.
The second 0^+ state, which has dominantly the (1/2^+)^2 configuration, is
shown to have a particularly enlarged structure. The kinetic
energy of the two valence neutrons occupying along the axis is
reduced remarkably due to the strong clustering and, simultaneously,
the spin-orbit interaction unexpectedly plays important role to make the energy
of this state much lower. The mixing of states with different spin structure is
shown to be important in negative-parity states. The experimentally observed
small-level spacing between 1^- and 2^- (~ 300 keV) is found to be an evidence
of this spin-mixing effect. ^{12}{Be} is also investigated using
model, in which four valence neutrons are considered to
occupy the (3/2^-)^2(1/2^+)^2 configuration. The energy surface of ^{12}Be is
shown to exhibit similar characteristics, that the remarkable
clustering and the contribution of the spin-orbit interaction make the binding
of the state with (3/2^-)^2(1/2^+)^2 configuration properly stronger in
comparison with the closed p-shell (3/2^-)^2(1/2^-)^2 configuration.Comment: 14 pages, 4 figure
Sintering behavior of ultrafine silicon carbide powders obtained by vapor phase reaction
The sintering behavior of ultrafine SiC powder with average particle size of about 0.01-0.06 microns produced by a vapor phase reaction of the Me4Si-H2 system was studied at the temperature range of 1400-2050 deg. It was found that the homogeneous dispersion of C on SiC particles is important to remove the surface oxide layer effectively. B and C and inhibitive effect on SiC grain growth
Microscopic description of light unstable nuclei with the stochastic variational method
The structure of the light proton and neutron rich nuclei is studied in a
microscopic multicluster model using the stochastic variational method. This
approach enables us to describe the weakly bound nature of these nuclei in a
consistent way. Applications for various nuclei Li, Be, B,
C, Be, B presented. The paper discusses the relation of
this model to other models as well as the possible extension for p and sd shell
nuclei.Comment: 11 pages, latex, no figures
ON THE LOW-TEMPERATURE ORDERING OF THE 3D ATIFERROMAGNETIC THREE-STATE POTTS MODEL
The antiferromagnetic three-state Potts model on the simple-cubic lattice is
studied using Monte Carlo simulations. The ordering in a medium temperature
range below the critical point is investigated in detail. Two different regimes
have been observed: The so-called broken sublattice-symmetry phase dominates at
sufficiently low temperatures, while the phase just below the critical point is
characterized by an effectively continuous order parameter and by a fully
restored rotational symmetry. However, the later phase is not the
permutationally sublattice symmetric phase recently predicted by the cluster
variation method.Comment: 20 pages with 9 figures in a single postscript file (compressed and
uuencoded by uufiles -gz -9) plus two big figures in postscript file
New effective nuclear forces with a finite-range three-body term and their application to AMD+GCM calculations
We propose new effective inter-nucleon forces with a finite-range three-body
operator. The proposed forces are suitable for describing the nuclear structure
properties over a wide mass number region, including the saturation point of
nuclear matter. The forces are applied to microscopic calculations of
() nuclei and O isotopes with a method of antisymmetrized molecular
dynamics. We present the characteristics of the forces and discuss the
importance of the finite-range three-body term.Comment: 15 pages, 11 figures, submitted to Phys.Rev.
Finite-size scaling for the Ising model on the Moebius strip and the Klein bottle
We study the finite-size scaling properties of the Ising model on the Moebius
strip and the Klein bottle. The results are compared with those of the Ising
model under different boundary conditions, that is, the free, cylindrical, and
toroidal boundary conditions. The difference in the magnetization distribution
function for various boundary conditions is discussed in terms of the
number of the percolating clusters and the cluster size. We also find
interesting aspect-ratio dependence of the value of the Binder parameter at
for various boundary conditions. We discuss the relation to the
finite-size correction calculations for the dimer statistics.Comment: 4 pages including 5 eps figures, RevTex, to appear in Phys. Rev. Let
Weak Lensing Mass Measurements of Substructures in COMA Cluster with Subaru/Suprime-Cam
We obtain the projected mass distributions for two Subaru/Suprime-Cam fields
in the southwest region (r\simlt 60') of the Coma cluster (z=0.0236) by weak
lensing analysis and detect eight subclump candidates. We quantify the
contribution of background large-scale structure (LSS) on the projected mass
distributions using SDSS multi-bands and photometric data, under the assumption
of mass-to-light ratio for field galaxies. We find that one of eight subclump
candidates, which is not associated with any member galaxies, is significantly
affected by LSS lensing. The mean projected mass for seven subclumps extracted
from the main cluster potential is = (5.06\pm1.30)10^12h^-1 M_sun
after a LSS correction. A tangential distortion profile over an ensemble of
subclumps is well described by a truncated singular-isothermal sphere model and
a truncated NFW model. A typical truncated radius of subclumps, r_t\simeq 35
h^-1 kpc, is derived without assuming any relations between mass and light for
member galaxies. The radius coincides well with the tidal radius, \sim42 h^-1
kpc, of the gravitational force of the main cluster. Taking into account the
incompleteness of data area, a projection effect and spurious lensing peaks, it
is expected that mass of cluster substructures account for 19 percent of the
virial mass, with 13 percent statistical error. The mass fraction of cluster
substructures is in rough agreement with numerical simulations.Comment: ApJ, accepted, 16 pages, 10 figures and 4 tables. High-resolution
pictures available at http://www.asiaa.sinica.edu.tw/~okabe/files/comaWL.pd
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