Our result is far more likely to be correct because the original result would require copper-bromine bonds that are stronger than the strongest known bonds in chemistry. The point on the far right is CuBr 35 and has a corrected formation energy of -0.526 eV/atom under the standard method, which is, not coincidentally, very similar to the standard method's bromine energy correction: -0.534 eV/atom. Since there are 36 atoms in the unit cell, this means the formation energy per unit cell is -18.94 eV. This would imply that if one had pure bromine and added 1/36th, or 3% copper, the formation of the bonds made by those copper atoms would release 18.94 eV per copper atom. For reference, the N-N triple bond has a bond energy of about 9.8 eV. So, the bonds formed by each of those copper atoms would have to be more than twice as energetically favorable as combining atomic nitrogen radicals into N 2 , which is an unphysical result.