The Vienna Ab Initio Simulation Package (VASP) version 6.2 was employed to facilitate DFT-based electronic structure spin-polarized simulations, utilizing the projector augmented wave (PAW) approach. The Perdew-Burke-Ernzerhof (PBE) exchange-correlation functional, augmented with Hubbard U corrections (PBE+U ), was applied to estimate the exchange-correlation potential. The influence of localized Cu-3d, Fe-3d, and Bi-5d orbitals in CFO and CBO has a mitigating effect on Coulomb interaction in the context of PBE. To handle the Coulomb interaction of the d electrons of the materials, the DFT+U method with the rotationally invariant formulation of Dudarev was employed for the d electrons of Cu (U = 8 eV), Fe (U = 4 eV), and Bi (U = 8 eV). The chosen U values are in agreement with published values for mixed transition metal oxides. The U parameter varies depending on the material, hence the U parameter was tested for Fe and Bi in the range of 0 to 9 eV as reported in tables S1 and S2. Applying U parameters helps preventing an underestimation of band gap energy values and magnetic moments. The band gap energy values, the magnetic moments, and the cell parameters were compared to literature. A Monkhorst-Pack grid was chosen according to a ⃗ k-spacing of at least 0.16 to sample the Brillouin Zone (BZ) during the full structural relaxation and optimization until the Hellmann-Feynman forces and self-consistent total electronic energy convergence reached below values of 10 -3 eV•A -1 and 10 -5 eV, respectively. The density of states (DOS) was visualized with the help of VASPKIT and was evaluated with a total electronic energy convergence criteria of 10 -6 eV and a denser ⃗ k-point grid of at least 0.08. The plane wave cut-off was set to 500 eV for both materials. The exact ⃗ k-point grid for each system can be found in the SI (S3 and S4). To prevent the creation of a net dipole moment within the unit cell, symmetric slabs with two identical terminations were employed to model the surfaces.