  The recently proposed dynamical effective field model (DEFM) is
quantitatively accurate for describing dynamical magnetic response of
ferrofluids. In paper I it is derived under the framework of dynamical density
functional theory, via which the original ensemble of bare Brownian particles
is mapped to an ensemble of dressed particles. However, it remains to clarify
how the characteristic rotational relaxation time of a dressed particle,
denoted by $\tau_r$, is quantitatively related to that of a bare particle,
denoted by $\tau^0_r$. By building macro-micro connections via two different
routes, I reveal that under some gentle assumptions $\tau_r$ can be identified
with the long-time rotational self-diffusion time. I further introduce two
simple but useful integrated correlation factors, describing the effects of
quasi-static (adiabatic) and dynamic (nonadiabatic) inter-particle
correlations, respectively. In terms of both correlation factors I reformulate
the dynamic magnetic susceptibility in an illuminating and elegant form.
Remarkably, it shows that the macro-micro connection is established via two
successive steps: a dynamical coarse-graining with nonadiabatic effects
accounted for by the dynamic factor, followed by equilibrium statistical
mechanical averaging captured by the static factor. Surprisingly,
$\tau_r/\tau^0_r$ is found insensitive to changes of particle volume fraction.
I provide a physical picture to explain it. Furthermore, an empirical formula
is proposed to characterize the dependence of $\tau_r/\tau^0_r$ on
dipole-dipole interaction strength. The DEFM supplemented with this formula
leads to parameter-free predictions in good agreement with results from
Brownian dynamics simulations. The theoretical developments presented in this
paper may have important consequences to studies of ferrofluid dynamics in
particular and other systems modelled by DDFTs in general.
