Fermi-Dirac distribution (source code)

= Fermi-Dirac distribution
{c}

= Fermi distribution
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{synonym}

The <Fermi-Dirac distribution> follows from <Fermi-Dirac statistics> and is $n(E)=[e^{\beta(E-\mu)}+1]^{-1}$.

The mean occupation of a fermionic one-particle state of energy $E$ is
$$
f(E)=\frac{1}{e^{\beta(E-\mu)}+1},
\qquad \beta=(k_BT)^{-1}.
$$
At zero temperature this becomes the step function $\mathbf 1_{E<E_F}$.