The effective-medium theory (EMT) potential is used as the energy calculator for initial benchmarking. The fast inertial relaxation engine 34 optimization routine is utilized to relax the structures, with forces on all individual atoms minimized to at least 0.1 eV Å-1 . DFT calculations are performed using GPAW with a real space implementation of the projector-augmented wave method. GPAW is run in the linear combination of atomic orbitals mode 36 with a double zeta basis set and RPBE exchange correlation functional. Calculations are run spin-polarised with a Fermi smearing of 0.05 eV in a non-periodic 32 × 32 × 32 Å unit cell.