Average Atom Model based on Quantum Hyper-Netted Chain Method

The study shows how to define "exactly" the average ion charge $Z_{\rm I}$ in the electron-ion model for plasmas and liquid metals: this definition comes out of the condition that a plasma consisting of electrons and nuclei can be described by the electron-ion model. Based on this definition of the average ion charge, the Quantum Hyper-Netted Chain (QHNC) method takes account of the resonant-state contribution to the bound electrons to form an ion. On the other hand, Blenski and coworkers have derived a formula to determine the electron density $n_0$ in a plasma as an electron-ion mixture by using the variational method with help of the local density approximation. Without use of any approximation, we derived the formula determining the electron density in an extended form on the basis of the DF theory. This formula is shown to be valid also for the QHNC method.