Two harmonically coupled Brownian particles in random media
Fachbereich Physik D-06099 Halle, Germany
Accepted: 8 March 2001
We study the behaviour of two Brownian particles coupled by an elastic harmonic force in a quenched disordered medium. We found that to first order in disorder strength, the relative motion weakens (with respect to the reference state of a Brownian particle with the double mass) the effect of the quenched forces on the centre-of-mass motion of the Brownian particles, so that the motion will become less subdiffusive (superdiffusive) for potential (solenoidal) disorder. The mean-square relative distance between the particles behaves in a different way depending on whether the particles are free to move or one particle is anchored in the space. While the effect of nonpotential disorder consists in increasing the mean-square distance in both cases, the potential disorder decreases the mean-square distance, when the particles are free to move, and increases it when one particle is anchored in the space.
PACS: 05.40.-a – Fluctuation phenomena, random processes, noise, and Browinan motion / 64.60.Cn – Order-disorder transformations; statistical mechanics of model systems / 36.20.-r – Macromolecules and polymer molecules
© EDP Sciences, 2001