Planar coincident site density is not a reliable predictor of grain boundary energy

The energies of grain boundaries in Ni and α-Fe have been compared to the planar coincident site density (PCSD) of grain boundaries with Σ ≤ 33 in the FCC and BCC structures. The PCSD is not correlated to the energies and is therefore not a useful predictor of the grain boundary energy. Because grain boundary relative area is often an indicator of grain boundary energy, measured grain boundary areas are also compared to the PCSD and again no correlation is observed. The absence of a correlation likely arises from the fact that coincident sites at grain boundaries do not generally have local coordination environments that are similar to the bulk sites and are therefore not expected to lead to reduced grain boundary energies.