2,708 research outputs found
On classification of Poisson vertex algebras
We describe a conjectural classification of Poisson vertex algebras of CFT
type and of Poisson vertex algebras in one differential variable (= scalar
Hamiltonian operators)
Dynamical excitonic effects in metals and semiconductors
The dynamics of an electron--hole pair induced by the time--dependent
screened Coulomb interaction is discussed. In contrast to the case where the
static electron--hole interaction is considered we demonstrate the occurrence
of important dynamical excitonic effects in the solution of the Bethe--Salpeter
equation.This is illustrated in the calculated absorption spectra of noble
metals (copper and silver) and silicon. Dynamical corrections strongly affect
the spectra, partially canceling dynamical self--energy effects and leading to
good agreement with experiment.Comment: Accepted for publication on Phys. Rev. Let
Quantitative analysis of Clausius inequality
In the context of driven diffusive systems, for thermodynamic transformations
over a large but finite time window, we derive an expansion of the energy
balance. In particular, we characterize the transformations which minimize the
energy dissipation and describe the optimal correction to the quasi-static
limit. Surprisingly, in the case of transformations between homogeneous
equilibrium states of an ideal gas, the optimal transformation is a sequence of
inhomogeneous equilibrium states.Comment: arXiv admin note: text overlap with arXiv:1404.646
Minimum dissipation principle in stationary non equilibrium states
We generalize to non equilibrium states Onsager's minimum dissipation
principle. We also interpret this principle and some previous results in terms
of optimal control theory. Entropy production plays the role of the cost
necessary to drive the system to a prescribed macroscopic configuration
Large deviation approach to non equilibrium processes in stochastic lattice gases
We present a review of recent work on the statistical mechanics of non
equilibrium processes based on the analysis of large deviations properties of
microscopic systems. Stochastic lattice gases are non trivial models of such
phenomena and can be studied rigorously providing a source of challenging
mathematical problems. In this way, some principles of wide validity have been
obtained leading to interesting physical consequences.Comment: Extended version of the lectures given by G. Jona-Lasinio at the 9th
Brazilian school of Probability, August 200
On the long range correlations of thermodynamic systems out of equilibrium
Experiments show that macroscopic systems in a stationary nonequilibrium
state exhibit long range correlations of the local thermodynamic variables. In
previous papers we proposed a Hamilton-Jacobi equation for the nonequilibrium
free energy as a basic principle of nonequilibrium thermodynamics. We show here
how an equation for the two point correlations can be derived from the
Hamilton-Jacobi equation for arbitrary transport coefficients for dynamics with
both external fields and boundary reservoirs. In contrast with fluctuating
hydrodynamics, this approach can be used to derive equations for correlations
of any order. Generically, the solutions of the equation for the correlation
functions are non-trivial and show that long range correlations are indeed a
common feature of nonequilibrium systems. Finally, we establish a criterion to
determine whether the local thermodynamic variables are positively or
negatively correlated in terms of properties of the transport coefficients.Comment: 4 page
Macroscopic current fluctuations in stochastic lattice gases
We study current fluctuations in lattice gases in the macroscopic limit
extending the dynamic approach to density fluctuations developed in previous
articles. More precisely, we derive large deviation estimates for the
space--time fluctuations of the empirical current which include the previous
results. Large time asymptotic estimates for the fluctuations of the time
average of the current, recently established by Bodineau and Derrida, can be
derived in a more general setting. There are models where we have to modify
their estimates and some explicit examples are introduced.Comment: 4 pages, LaTeX, Changed conten
Large deviations of the empirical current in interacting particle systems
We study current fluctuations in lattice gases in the hydrodynamic scaling
limit. More precisely, we prove a large deviation principle for the empirical
current in the symmetric simple exclusion process with rate functional I. We
then estimate the asymptotic probability of a fluctuation of the average
current over a large time interval and show that the corresponding rate
function can be obtained by solving a variational problem for the functional I.
For the symmetric simple exclusion process the minimizer is time independent so
that this variational problem can be reduced to a time independent one. On the
other hand, for other models the minimizer is time dependent. This phenomenon
is naturally interpreted as a dynamical phase transition.Comment: 26 page
Seasonal variations in Greenland Ice Sheet motion : Inland extent and behaviour at higher elevations
Peer reviewedPreprin
Bound excitons in time-dependent density-functional-theory: optical and energy-loss spectra
A robust and efficient frequency dependent and non-local exchange-correlation
is derived by imposing time-dependent density-functional
theory (TDDFT) to reproduce the many-body diagrammatic expansion of the
Bethe-Salpeter polarization function. As an illustration, we compute the
optical spectra of LiF, \sio and diamond and the finite momentum transfer
energy-loss spectrum of LiF. The TDDFT results reproduce extremely well the
excitonic effects embodied in the Bethe-Salpeter approach, both for strongly
bound and resonant excitons. We provide a working expression for that
is fast to evaluate and easy to implement.Comment: 4 pages, 2 figures. To appear in Phys. Rev. Let
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