“…One first defines the coarse-grain averagen(x, y) of the spatial density n(x, y) = N|ψ(x, y)| 2 , in order to smooth the rapid variations at the vortex cores. The energy functional (15) can be written in terms ofn instead of n, provided the interaction parameter G is renormalized to bG, where b ≃ 1.16 is the so-called Abrikosov parameter [68]. This parameter arises from the discreteness of the vortex distribution: since the wave function ψ(x, y) must vanish at the vortex location, the average value of |ψ| 4 over the unit cell, hence the interaction energy, is larger than the result obtained if |ψ| was quasi-uniform over the cell.…”