  An important physical model describing the dynamics of dilute weakly ionized
plasmas in the collisional kinetic theory is the Vlasov-Poisson-Boltzmann
system for which the plasma responds strongly to the self-consistent
electrostatic force. This paper is concerned with the electron dynamics of
kinetic plasmas in the whole space when the positive charged ion flow provides
a spatially uniform background. We establish the global existence and optimal
convergence rates of solutions near a global Maxwellian to the Cauchy problem
on the Vlasov-Poisson-Boltzmann system for angular cutoff soft potentials with
$-2\leq \gamma<0$. The main idea is to introduce a time dependent weight
function in the velocity variable to capture the singularity of the
cross-section at zero relative velocity.
