Core structures and energetics for BCC Fe dislocations: a[100] (010) edge, a[100] (011) edge, a/2[-1-11] (1-10) edge, and a/2[111] (1-10) 71 degree mixed dislocation. The structures are relaxed in density functional theory (DFT) using lattice Green function-based flexible boundary conditions (LGF FBC). The energetics of the dislocations are calculated using the energy density method (EDM) integrated over Bader volumes and charge-neutral volumes using the weight method (doi:10.1063/1.3553716). For comparison, we include the computation of the same dislocations using significantly larger cells with the Mendelev EAM potential and Zhang GAP potential for Fe, which had been earlier shown to perform well at predicting the core structures.