11,750 research outputs found
The suppression of superconductivity in Mn substituted MgCNi
We report the effect of doping Mn in the isostructural MgCNiMn
(x = 0-0.05) compounds. Magnetic susceptibility, resistivity,
magneto-resistance, and specific heat studies show evidence of localized
moments and Kondo effect in samples with x0. The rapid suppression of
superconductivity ( -21K/at.% Mn) in these compounds is a consequence of
pair breaking effects due to moment formation on Mn.Comment: 9 figures, Accepted for publication in Physical Review B, Added
reference
Dynamic Heterogeneity in Fully Miscible Blends of Polystyrene with Oligostyrene
Binary blends of polystyrene with oligostyrene are perfectly miscible (χ=0) yet dynamically heterogeneous. This is evidenced by independent probing of the dipole relaxation perpendicular to the backbone by dielectric spectroscopy and molecular dynamics. The self-concentration model with a single intra-molecular length scale qualitatively describes the slower segmental dynamics. A quantitative comparison based on MD however, requires a composition-dependent length scale. The pertinent dynamic length scale that best describes the slow segmental dynamics in miscible blends relates to both intra- and inter-molecular contributions
Adaptive Resolution Molecular Dynamics Simulation: Changing the Degrees of Freedom on the Fly
We present a new adaptive resolution technique for efficient particle-based
multiscale molecular dynamics (MD) simulations. The presented approach is
tailor-made for molecular systems where atomistic resolution is required only
in spatially localized domains whereas a lower mesoscopic level of detail is
sufficient for the rest of the system. Our method allows an on-the-fly
interchange between a given molecule's atomic and coarse-grained level of
description, enabling us to reach large length and time scales while spatially
retaining atomistic details of the system. The new approach is tested on a
model system of a liquid of tetrahedral molecules. The simulation box is
divided into two regions: one containing only atomistically resolved
tetrahedral molecules, the other containing only one particle coarse-grained
spherical molecules. The molecules can freely move between the two regions
while changing their level of resolution accordingly. The coarse-grained and
the atomistically resolved systems have the same statistical properties at the
same physical conditions.Comment: 17 pages, 11 figures, 5 table
Irreversible Processes in a Universe modelled as a mixture of a Chaplygin gas and radiation
The evolution of a Universe modelled as a mixture of a Chaplygin gas and
radiation is determined by taking into account irreversible processes. This
mixture could interpolate periods of a radiation dominated, a matter dominated
and a cosmological constant dominated Universe. The results of a Universe
modelled by this mixture are compared with the results of a mixture whose
constituents are radiation and quintessence. Among other results it is shown
that: (a) for both models there exists a period of a past deceleration with a
present acceleration; (b) the slope of the acceleration of the Universe
modelled as a mixture of a Chaplygin gas with radiation is more pronounced than
that modelled as a mixture of quintessence and radiation; (c) the energy
density of the Chaplygin gas tends to a constant value at earlier times than
the energy density of quintessence does; (d) the energy density of radiation
for both mixtures coincide and decay more rapidly than the energy densities of
the Chaplygin gas and of quintessence.Comment: 8 pages, 1 figure, to be published in GR
Normal origamis of Mumford curves
An origami (also known as square-tiled surface) is a Riemann surface covering
a torus with at most one branch point. Lifting two generators of the
fundamental group of the punctured torus decomposes the surface into finitely
many unit squares. By varying the complex structure of the torus one obtains
easily accessible examples of Teichm\"uller curves in the moduli space of
Riemann surfaces. The p-adic analogues of Riemann surfaces are Mumford curves.
A p-adic origami is defined as a covering of Mumford curves with at most one
branch point, where the bottom curve has genus one. A classification of all
normal non-trivial p-adic origamis is presented and used to calculate some
invariants. These can be used to describe p-adic origamis in terms of glueing
squares.Comment: 21 pages, to appear in manuscripta mathematica (Springer
- …