1,124 research outputs found
Non-universal equilibrium crystal shape results from sticky steps
The anisotropic surface free energy, Andreev surface free energy, and
equilibrium crystal shape (ECS) z=z(x,y) are calculated numerically using a
transfer matrix approach with the density matrix renormalization group (DMRG)
method. The adopted surface model is a restricted solid-on-solid (RSOS) model
with "sticky" steps, i.e., steps with a point-contact type attraction between
them (p-RSOS model). By analyzing the results, we obtain a first-order shape
transition on the ECS profile around the (111) facet; and on the curved surface
near the (001) facet edge, we obtain shape exponents having values different
from those of the universal Gruber-Mullins-Pokrovsky-Talapov (GMPT) class. In
order to elucidate the origin of the non-universal shape exponents, we
calculate the slope dependence of the mean step height of "step droplets"
(bound states of steps) using the Monte Carlo method, where p=(dz/dx,
dz/dy)$, and represents the thermal averag |p| dependence of , we
derive a |p|-expanded expression for the non-universal surface free energy
f_{eff}(p), which contains quadratic terms with respect to |p|. The first-order
shape transition and the non-universal shape exponents obtained by the DMRG
calculations are reproduced thermodynamically from the non-universal surface
free energy f_{eff}(p).Comment: 31 pages, 21 figure
Effects of electron correlations and chemical pressures on superconductivity of β''-type organic compounds
We investigate low-temperature electronic states of the series of organic conductors β'' - [bis(ethylenedithio)tetrathiafulvalene] 4[(H3O)M(C2O4)3] G, where M and G represent trivalent metalions and guest organic molecules, respectively. Our structural analyses reveal that the replacement of M and G give rise to systematic change in the cell parameters, especially in the b-axis length, which has a positive correlation with the superconducting transition temperature Tc. Analysis of temperature and magnetic field dependences of the electrical resistance including the Shubnikov–de Haas oscillations elucidates that the variation of charge disproportionation, the effective mass, and the number of itinerant carriers can be systematically explained by the change of the b-axis length. The changes of the transfer integrals induced by stretching/compressing the b axis are confirmed by the band calculation. We discuss that electron correlations in quarter-filled electronic bands lead to charge disproportionation and the possibility of a novel pairing mechanism of superconductivity mediated by charge degrees of freedom
Vicinal Surface with Langmuir Adsorption: A Decorated Restricted Solid-on-solid Model
We study the vicinal surface of the restricted solid-on-solid model coupled
with the Langmuir adsorbates which we regard as two-dimensional lattice gas
without lateral interaction. The effect of the vapor pressure of the adsorbates
in the environmental phase is taken into consideration through the chemical
potential. We calculate the surface free energy , the adsorption coverage
, the step tension , and the step stiffness by
the transfer matrix method combined with the density-matrix algorithm. Detailed
step-density-dependence of and is obtained. We draw the roughening
transition curve in the plane of the temperature and the chemical potential of
adsorbates. We find the multi-reentrant roughening transition accompanying the
inverse roughening phenomena. We also find quasi-reentrant behavior in the step
tension.Comment: 7 pages, 12 figures (png format), RevTeX 3.1, submitted to Phys. Rev.
On control of singleton attractors in multiple Boolean networks: integer programming-based method
published_or_final_versionThe Twelfth Asia Pacific Bioinformatics Conference (APBC 2014), Shanghai, China. 17-19 January 2014. In BMC Systems Biology, 2014, v. 8, Suppl. 1, article no. S
Non semi-simple sl(2) quantum invariants, spin case
Invariants of 3-manifolds from a non semi-simple category of modules over a
version of quantum sl(2) were obtained by the last three authors in
[arXiv:1404.7289]. In their construction the quantum parameter is a root of
unity of order where is odd or congruent to modulo . In this
paper we consider the remaining cases where is congruent to zero modulo
and produce invariants of -manifolds with colored links, equipped with
generalized spin structure. For a given -manifold , the relevant
generalized spin structures are (non canonically) parametrized by
.Comment: 13 pages, 16 figure
Fluctuations of an Atomic Ledge Bordering a Crystalline Facet
When a high symmetry facet joins the rounded part of a crystal, the step line
density vanishes as sqrt(r) with r denoting the distance from the facet edge.
This means that the ledge bordering the facet has a lot of space to meander as
caused by thermal activation. We investigate the statistical properties of the
border ledge fluctuations. In the scaling regime they turn out to be
non-Gaussian and related to the edge statistics of GUE multi-matrix models.Comment: Version with major revisions -- RevTeX, 4 pages, 2 figure
Self-Consistent Tensor Product Variational Approximation for 3D Classical Models
We propose a numerical variational method for three-dimensional (3D)
classical lattice models. We construct the variational state as a product of
local tensors, and improve it by use of the corner transfer matrix
renormalization group (CTMRG), which is a variant of the density matrix
renormalization group (DMRG) applied to 2D classical systems. Numerical
efficiency of this approximation is investigated through trial applications to
the 3D Ising model and the 3D 3-state Potts model.Comment: 12 pages, 6 figure
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