ABSTRACT
This chapter provides an understanding of the ensemble method and how the ensemble method is used to go from molecular models to bulk thermodynamic averages to students. Molecular models provide a comprehensive list of allowed of microstates with different properties, but on their own, they should not define the equilibrium distribution. The chapter describes the ideas behind the statistical thermodynamic approach by considering the properties of an isolated system. Using molecular model, the chapter shows that one way to get thermodynamic averages is to build a dynamic model and average over time. The ensemble approach is the central method in statistical thermodynamics. Using the ensemble approach, the chapter finds the most probable distribution for an isolated ensemble, also referred to as a "microcanonical ensemble". The chapter defines an important function, the "partition function", which encodes the probability of each microstate.
