The diffusion equation of the spheroid

The correlation function of the Brownian rotational diffusion of a spheroid is

$${\frac{{1}}{{5}}} \sum^{1}_{{i=-1}} {\frac{{\tau}}{{\tau_i}}}$$ (15.147)

where c_i are the weights of the three exponential terms which are dependent on the orientation of the XH bond vector and τ_i are the correlation times of the three exponential terms.