Spin-summed density of states
= Spin-summed density of states
{title2=$\nu=2\nu_s$}
For a spin-degenerate band, the total <density of states> includes both spin species and is twice the <single-spin density of states>. Per lattice site, $\nu(\epsilon)=2N^{-1}\sum_k\delta(\epsilon-\epsilon_k)$. Using a separate explicit spin sum then requires a compensating factor one half when converting momentum sums. The normalization matters in the <Stoner criterion>.