Charged Brownian particles: Kramers and Smoluchowski equations and the hydrothermodynamical picture
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2011-05-01
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Resumo
We consider a charged Brownian gas under the influence of external and non-uniform electric, magnetic and mechanical fields, immersed in a non-uniform bath temperature. With the collision time as an expansion parameter, we study the solution to the associated Kramers equation, including a linear reactive term. To the first order we obtain the asymptotic (overdamped) regime, governed by transport equations, namely: for the particle density, a Smoluchowski- reactive like equation; for the particle's momentum density, a generalized Ohm's-like equation; and for the particle's energy density, a MaxwellCattaneo-like equation. Defining a nonequilibrium temperature as the mean kinetic energy density, and introducing Boltzmann's entropy density via the one particle distribution function, we present a complete thermohydrodynamical picture for a charged Brownian gas. We probe the validity of the local equilibrium approximation, Onsager relations, variational principles associated to the entropy production, and apply our results to: carrier transport in semiconductors, hot carriers and Brownian motors. Finally, we outline a method to incorporate non-linear reactive kinetics and a mean field approach to interacting Brownian particles. © 2011 Elsevier B.V. All rights reserved.
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Brownian motion, Brownian motors, Carrier transport, Dissipative dynamics, Evolution of nonequilibrium systems, Kramers equation, Smoluchowski equation, Kramers equations, Distribution functions, Entropy, Variational techniques, Brownian movement
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Physica A: Statistical Mechanics and its Applications, v. 390, n. 9, p. 1591-1601, 2011.