Subject: Q: Pure Rotational Diffusion (Langevin)

From: [email-masked] (Gabriel Berriz)
Date: Mon, 30 Sep 1996 12:12:15 -0400

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.