Lahiri, Rangan and Arvind, * and Sain, Anirban (2004) Brownian motion in a classical ideal gas:A microscopic approach to Langevin's equation. In: Pramana:Journal of Physics, 62 (5). pp. 10151028.

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Abstract
We present an insightful `derivation' of the Langevin equation and the fluctuation dissipation theorem in the specific context of a heavier particle moving through an ideal gas of much lighter particles. The Newton's law of motion (mxx = F) for the heavy particle reduces to a Langevin equation (valid on a coarser timescale) with the assumption that the lighter gas particles follow a Boltzmann velocity distribution. Starting from the kinematics of the random collisions we show that (1) the average force (F) oc x x and (2) the correlation function of the fluctuating force rl = F  (F) is related to the strength of the average force.
Item Type:  Journal Article 

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Additional Information:  Copyright of this article belongs to Indian academy of Sciences. 
Keywords:  Brownian motion;Fluctuation dissipation theorem;Ideal gas 
Department/Centre:  Division of Physical & Mathematical Sciences > Physics 
Date Deposited:  01 Jul 2008 
Last Modified:  20 Jan 2012 06:31 
URI:  http://eprints.iisc.ernet.in/id/eprint/11387 
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