  Theoretical modelling of ionization potential depression and the related
ionization equilibrium in dense plasmas, in particular in warm/hot dense
matter, represents a significant challenge due to ionic coupling and electronic
degeneracy effects. We present a quantum statistical model based on dynamical
structure factors for the ionization potential depression, where quantum
exchange and dynamical correlation effects in plasma environments are
consistently and systematically taken into account in terms of the concept of
self-energy. Under the condition of local thermodynamic equilibrium, the charge
state distribution (or ionic fraction) characterized by the ionization balance
is obtained by solving the coupled Saha equations. Calculations for the
ionization potential depression of different chemical elements are performed
with the electronic and ionic structure factors. The ionic structure factors
are determined by solving the Ornstein-Zernike equation in combination with the
hypernetted-chain equation. As a further application of our approach, we
present results for the charge state distribution of aluminium plasmas at
several temperatures and densities.
