Bose and Fermi thermal occupations
Indistinguishable particles have different equilibrium state populations.
Key knowledge
For ideal noninteracting particles at grand-canonical equilibrium, a single state's mean occupation is 1/[e^((ε−μ)/(k_BT))+1] for fermions and 1/[e^((ε−μ)/(k_BT))−1] for bosons.
Values and equations
n̄_F(ε) = 1/[e^((ε−μ)/(k_BT))+1]; n̄_B(ε) = 1/[e^((ε−μ)/(k_BT))−1]
- n̄_F, n̄_B
- Mean number occupying one state
- ε, μ
- State energy and chemical potential J
- k_B
- Boltzmann constant J K⁻¹
- T
- Absolute temperature K
Conditions and scope
- T > 0; ε and μ share an energy zero. The formula is per state, without a degeneracy multiplier.
- For finite bosonic occupations μ < the lowest state energy; a condensate and the limiting ground-state population need separate treatment.
Sources · 1
References
Sources retain their recorded scope. A source link alone does not establish verification of every statement.
Evidence and review
Lecture 8 pages 6 and 9: single-state distributions, fermion occupancy and chemical potential.
2026-10-10 · Ideal equilibrium occupation functions only; extra classical normalization factors and interacting spectra are excluded.
Entry details
Permanent link to this entry ↗- Record identity
- physics-bose-fermi-occupation
- Revision
- university-reference.1
- Structured reference record
- University reference · University core expansion