  We suggest the diffuse approach to the relaxation processes within the
kinetic theory for the Wigner distribution function. The diffusion and drift
coefficients are evaluated taking into consideration the interparticle
collisions on the distorted Fermi surface. Using the finite range interaction,
we show that the momentum dependence of the diffuse coefficient $D_{p}(p)$ has
a maximum at Fermi momentum $p=p_{F}$ whereas the drift coefficient $K_{p}(p)$
is negative and reaches a minimum at $p\approx p_{F}$. For a cold Fermi system
the diffusion coefficient takes the non-zero value which is caused by the
relaxation on the distorted Fermi-surface at temperature $T=0$. The numerical
solution of the diffusion equation was performed for the particle-hole
excitation in a nucleus with $A=16$. The evaluated relaxation time
$\tau_{r}\approx 8.3\cdot 10^{-23}\mathrm{s}$ is close to the corresponding
result in a nuclear Fermi-liquid obtained within the kinetic theory.
