1,328 research outputs found
Staying Thermal with Hartree Ensemble Approximations
We study thermal behavior of a recently introduced Hartree ensemble
approximation, which allows for non-perturbative inhomogeneous field
configurations as well as for approximate thermalization, in the model
in 1+1 dimensions. Using ensembles with a free field thermal distribution as
out-of-equilibrium initial conditions we determine thermalization time scales.
The time scale for which the system stays in approximate quantum thermal
equilibrium is an indication of the time scales for which the approximation
method stays reasonable. This time scale turns out to be two orders of
magnitude larger than the time scale for thermalization, in the range of
couplings and temperatures studied. We also discuss simplifications of our
method which are numerically more efficient and make a comparison with
classical dynamics.Comment: 19 pages latex; extensively rewritten to improve presentation, data
essentially unchanged, analysis sharpened and one table adde
The Hartree ensemble approximation revisited: The "symmetric phase"
The Hartree ensemble approximation is studied in the ``symmetric phase'' of
1+1 dimensional lambda phi^4 theory. In comparison with the ``broken phase''
studied previously, it is shown that the dynamical evolution of observables
such as the particle distribution, energy exchange and auto-correlation
functions, is substantially slower. Approximate thermalization is found only
for relatively large energy densities and couplings.Comment: 17 pages RevTeX, 16 figures, 3 tables, uses amsmath and feynmp.
Extended some sections, reordered Sec.IV, added 3 refs, numerical typo
corrected, published versio
Self-assembled electron-rich receptors: from molecular polygons to polyhedra
International audienc
Finite Temperature Simulations from Quantum Field Dynamics?
We describe a Hartree ensemble method to approximately solve the Heisenberg
equations for the \phi^4 model in 1+1 dimensions. We compute the energies and
number densities of the quantum particles described by the \phi field and find
that the particles initially thermalize with a Bose-Einstein distribution for
the particle density. Gradually, however, the distribution changes towards
classical equipartition. Using suitable initial conditions quantum
thermalization is achieved much faster than the onset of this undesirable
equipartition. We also show how the numerical efficiency of our method can be
significantly improved.Comment: Lattice 2000 (Finite Temperature), 4 pages, 5 figures; title
correcte
Coordination-driven self-assembly of electron-rich tetrathiafulvalene-based architectures
Date du colloque : 12/2010International audienc
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