2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/25191A vortex line, shaped by a zigzag of pinning centers, is described here through a three-dimensional unit cell containing two pinning centers positioned symmetrically with respect to its center. The unit cell is a cube of side $L=12ξ$, the pinning centers are insulating spheres of radius $R$, taken within the range $0.2ξ$ to $3.0ξ$, $ξ$ being the coherence length. We calculate the free energy density of these systems in the framework of the Ginzburg-Landau theory.Submitted to Braz. Jour. Phys. (http://www.sbfisica.org.br/bjp) 11 pages, 6 figures, 1 table, LaTex 2eSuperconductivitytext