26,326 research outputs found
Finite temperature behavior of impurity doped Lithium cluster {\em viz} LiSn
We have carried out extensive isokinetic {\it ab initio} molecular dynamic
simulations to investigate the finite temperature properties of the impurity
doped cluster LiSn along with the host cluster Li. The data obtained
from about 20 temperatures and total simulation time of at least 3 ns is used
to extract thermodynamical quantities like canonical specific heat. We observe
a substantial charge transfer from all Li atoms to Sn which inturn weakens the
Li-Li bonds in LiSn compared to the bonds in Li. This weakening of
bonds changes the finite temperature behavior of LiSn significantly.
Firstly, LiSn becomes liquid-like around 250 K, a much lower temperature
than that of Li (~425 K). Secondly, an additional quasirotational
motion of lithium atoms appears at lower temperatures giving rise to a shoulder
around 50 K in the specific heat curve of LiSn. The peak in the specific
heat of Li is very broad and the specific heat does not show any premelting
features.Comment: 16 pages, 10 figures Submitted to J. Chem. Phy
Quantum Hertz entropy increase in a quenched spin chain
The classical Hertz entropy is the logarithm of the volume of phase space
bounded by the constant energy surface; its quantum counterpart, the quantum
Hertz entropy, is , where the quantum operator specifies the number of states with energy below a given energy eigenstate.
It has been recently proved that, when an isolated quantum mechanical system is
driven out of equilibrium by an external driving, the change in the expectation
of its quantum Hertz entropy cannot be negative, and is null for adiabatic
driving. This is in full agreement with the Clausius principle. Here we test
the behavior of the expectation of the quantum Hertz entropy in the case when
two identical XY spin chains initially at different temperatures are quenched
into a single XY chain. We observed no quantum Hertz entropy decrease. This
finding further supports the statement that the quantum Hertz entropy is a
proper entropy for isolated quantum systems. We further quantify how far the
quenched chain is from thermal equilibrium and the temperature of the closest
equilibrium.Comment: 9 pages, 5 figure
The Charged Neutrino: A New Approach to the Solar Neutrino Problem
We have considered the effect of the reduction of the solar neutrino flux on
earth due to the deflection of the charged neutrino by the magnetic field of
the solar convective zone. The antisymmetry of this magnetic field about the
plane of the solar equator induces the anisotropy of the solar neutrino flux
thus creating the deficit of the neutrino flux on the earth. The deficit has
been estimated in terms of solar and neutrino parameters and the condition of a
50 \% deficit has been obtained: Q_{\nu} gradH \agt 10^{-18} eG/cm where
is the neutrino electric charge, is the gradient of the solar
toroidal magnetic field, e is the electron charge. Some attractive experimental
consequences of this scenario are qualitatively discussed.Comment: 15 pages, UM-P/94-26, in REVTE
Maverick Examples Of Coset Conformal Field Theories
We present coset conformal field theories whose spectrum is not determined by
the identification current method. In these ``maverick'' cosets there is a
larger symmetry identifying primary fields than under the identification
current. We find an A-D-E classification of these mavericks. }Comment: 16pages , reportSWAT-93-0
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