ABSTRACT
The grand canonical ensemble, which completes the ensemble set, is discussed in the chapter. In this chapter, it is pointed out that, for systems consisting of macroscopically large numbers of particles, the authors can choose whichever ensemble is most convenient for a particular calculation. Before introducing the grand canonical distribution, the authors first consider the equilibrium conditions for two systems that interact thermally, mechanically, and via particle exchange. The canonical distribution is derived for a system in thermal contact with a large heat bath at specific temperature. The grand canonical ensemble consists of a large number of replicas of the combined small system 1 plus reservoir 2. The expressions given in this chapter for the grand canonical distribution and the grand partition function are quite general, and it is helpful to consider a specific system to see how the summations are carried out.
