Multiplicity (statistical mechanics)

In statistical mechanics, multiplicity (also called statistical weight) refers to the number of microstates corresponding to a particular macrostate of a thermodynamic system.^[1] Commonly denoted ${\displaystyle \Omega }$, it is related to the configuration entropy of an isolated system^[2] via Boltzmann's entropy formula $${\displaystyle S=k_{\text{B}}\log \Omega ,}$$ where ${\displaystyle S}$ is the entropy and ${\displaystyle k_{\text{B}}}$ is the Boltzmann constant.