Maxwell-Boltzmann statistic


The Maxwell-Boltzmann statistic or distribution (not to be confused with the other Maxwell-Boltzmann distribution) is a real, continuous Probability distribution that describes the behavior of a system of NN classical particles in thermal equilibrium. Its Probability density function is

ni=1eβ(εiμ)=zeβεi\langle n_{i} \rangle =\frac{1}{e^{\beta(\varepsilon_{i}-\mu)}}=ze^{-\beta \varepsilon_{i}}

ni\langle n_{i} \rangle is the average number of particles in the ii-th single-particle state of energy εi\varepsilon_{i}, μ\mu is the system chemical potential, β=1/kBT\beta=1/k_{B}T is the inverse temperature, with kBk_{B} the Boltzmann constant and TT the temperature, and zz is the fugacity. The normalization constant is

ini=N\sum_{i}n_{i}=N

This distribution is closely related to its quantum equivalents, the Fermi-Dirac distribution and the Bose-Einstein distribution. These converge to the Maxwell-Boltzmann statistic at high temperature.