Ensembles and Partition Functions

This lecture introduces the concept of ensembles in statistical thermodynamics, covering canonical, microcanonical, and grand canonical ensembles. It explains partition functions for molecules, electrons, and phonons, as well as Fermi-Dirac and Bose-Einstein distributions. The instructor discusses the ergodic hypothesis, microscopic configurations, and the additiveness of entropy. The lecture also delves into the microcanonical ensemble, entropy, and the behavior of particles in equilibrium. Furthermore, it explores the canonical ensemble for systems with fixed temperature, volume, and number of particles, emphasizing the logarithmic additiveness of entropy. The instructor concludes by discussing the grand canonical ensemble for systems exchanging energy and particles with a reservoir.