ROTATIONAL BROWNIAN-MOTION OF A 2-DIMENSIONAL RIGID ROTATOR - RELAXATION AND STEADY-STATE REGIMES

Exact analytical expressions for the dielectric and Kerr functions in both relaxation and steady-state regimes are explicitly calculated by solving the Fokker-Planck-Kramers (FPK) equation for the rotational Br ownian motion of a rigid rotator in 2D. The response functions which a re thus obtained, generalize and extend all the results recently publi shed on the topic. The particular case of the Debye-Smoluchowski diffu sion model is straighfforwardly recovered. We give also the entropy fo rmula for the rotator system and analyse the implication of the second principle of thermodynamics for the steady-state dielectric and Kerr functions.