Topological charge of a two-dimensional nematic disclination (source code)

= Topological charge of a two-dimensional nematic disclination
{title2=$q=\Delta\theta/(2\pi)$}

For a continuous director angle around a closed counterclockwise circuit, the enclosed <topological charge> is $q=\Delta\theta/(2\pi)$. Since $\theta$ is defined modulo $\pi$, elementary <nematic disclinations> can have $q=\pm1/2$.