Equation of state of compressed matter: a simple statistical model

We propose a simple approach for studying systems of compressed matter based on the Thomas–Fermi statistical model of single atom. The central point of our work is the development of the concept of “statistical ionization” by compression; in simple terms, we calculate the fraction of electrons within the atom whose positive energy, due to the compression, exceeds the negative binding energy electron–nucleus. Next we extend this concept from a single atom to macroscopic systems and write the corresponding equation of state. Positive aspects as well as limitations of the model are illustrated and discussed throughout the paper.