“…For the evolution of Wwith time, we define G(;&s, fil, t' Pa, Pe, t) as the probability that amolecule with orientation J;&a ;&'I at time t' will rotate into a new orientation $P&a, AeI by time t. Thus, W(jia, ;&e, t) = ffW(J&a'',JL t') G(pa, , t' ;a,pe, t) djda. d (7) Here we understand that both W and G contain a factor 6(P,aflecos X) which assures the fixed angle between the two moments. For the isotropic sample, stationary distribution W5 is given by WS(paLe) = ( 1/87r2) (La6 gecos X).…”