Question

Why is the partition function important, and what does the partition function measure?

Answer 1

partition function explains the statistical properties of a system in thermodynamic equilibrium[citation. It give relation ship thermodynamic state variables, such as the temperature and volume. Most of the aggregate thermodynamic variables of the system, such as the total energy, free energy, entropy, and pressure, can be expressed in terms of the partition function or its derivatives. There are actually several different types of partition functions, each corresponding to different types of statistical ensemble (or, equivalently, different types of free energy.) The canonical partition function applies to a canonicalensemble, in which the system is allowed to exchange heat with the environment at fixed temperature, volume, andnumber of particles. canonical partition function applies to a grand canonical ensemble, in which thesystem can exchange both heat and particles with the environment, at fixed temperature, volume, and chemicalpotential. The partition function has many physical meanings, as discussed in Meaning and significance.