Q: Pure Rotational Diffusion (Langevin)

[berriz "at@at" chasma.harvard.edu (Gabriel Berriz)]

 I am studying the behavior of a three-dimensional arrangement of rigid
 particles that are translationally fixed, but may rotate around any
 axis.  (No symmetries are assumed for the particles, so no axis is
 privileged.)  To each pair of particles corresponds a potential
 energy, which depends on the orientations of the particles relative to
 each other, and the distance between them.  (The internal energy of
 the ensemble is the sum of all the pairwise energies).  I am currently
 using a Langevin-type formalism to study the effect of applying a
 thermal rotational fluctuation (to each particle) on the ensemble's
 steady-state configuration.
 These studies have yielded some rather strange results (briefly, the
 stability of the system decreases dramatically when going from 6 to 7
 particles, plus some other strange details).  Therefore, I am now
 conducting a detailed and thorough troubleshooting of my system.  To
 this end, I am interested in learning as much as possible about
 existing work on Langevin models of (purely) rotational diffusion of
 (asymmetrical) particles.  I would greatly appreciate the readership's
 pointers to the literature.