Anisotropy energy

The continuous form of the anisotropy energy is computed by integrating the
anisotropy energy $w_{\mathrm{an}}$ (Aharoni, 2000), which is in the form of either equation 2.5 or 2.8:

$$\mathcal{E}_{\mathrm{an}} = \int_V w_{\mathrm{an}} \mathrm{d}^3r %+ \int_S w_s \mathrm{d}^2r$$ (2.27)

$\mathcal{E}_{\mathrm{an}}$The anisotropy energy of a system