THE EQUATION OF STATE IN THE CHEMICAL PICTURE - A GRAND-CANONICAL APPROACH .2. THE OCCUPATION NUMBER OF MOLECULES AND ATOMS

The grand-canonical approach for the equation of state in the chemical picture (Paper 1) is used to calculate the occupation numbers of mole cules and atoms for a stellar gas. The configurations of molecular hyd rogen and negative hydrogen ions, as well as atomic configurations, ar e included. The occupation probability is incorporated into the EOS fo rmulation to explain pressure ionization of bound atomic configuration s and pressure dissociation of molecular configurations. Two solutions of the EOS are found in the region of pressure ionization of HI. This is due to the behavior of positive feedback of the occupation probabi lity for interpreting the perturbation by charged particles. The calcu lation results indicate that the grand-canonical approach can include both atomic configurations and molecular configurations, and that the occupation probability incorporated by the approach can produce pressu re dissociation and ionization in both neutral and partially ionized g ases.