4.9: Summary of Major Ensembles
( \newcommand{\kernel}{\mathrm{null}\,}\)
boundary | variables | probability of microstate | p.f. | master function | |
microcanonical | adiabatic (no-skid) | E, V, N | dΓN!h3N01Ω or 0 | Ω | S(E, V, N) = kB ln Ω |
canonical | heat bath | T, V, N | dΓe−βH(Γ)N!h3N01Z | Z | F(T, V, N) = −kBT lnZ |
grand canonical | heat bath, with holes | T, V,
μ |
dΓNe−βH(ΓN)−αNN!h3N01Ξ | Ξ | Π(T, V, µ) = −kBT ln Ξ |
In all cases, the partition function (p.f. in the above table) is the normalization factor
p.f.=∑ microstates unnormalized probability.