Introduction

In Part II we saw that the canonical ensemble emerges naturally from the ensemble that characterizes an isolated system (the micro canonical ensemble). There it was demonstrated in the special case of a simple system — the paramagnet, but the argument can be generalized in a natural way to any system. The canonical description is the most useful one, as in most practical cases it is possible to control the temperature and not the energy of the system. Indeed we will use the canonical ensemble, as a starting point in the analysis of most systems we shall consider…