The C-Fe and C-C interactions near to a body-centred cubic Fe vacancy were analysed by using DFT calculations. A cell containing 14 atoms was used to simulate the local environment of the Fe vacancy. Carbon atoms were positioned in their local energy minimum configurations. The most stable positions for the C atoms in the vacancy region were found at about 1.23Å from the vacancy centre and near the first nearest-neighbour octahedral sites. Changes in the electronic structure of Fe atoms near a vacancy were analysed. The Fe-Fe bonds surrounding the vacancy weaken their bond when the C atoms were present. This bond weakening was a consequence of C-Fe bond formation. The Fe-C interactions occurred mainly via Fe 4s orbitals, with a lesser participation of Fe 3p orbitals. There was an electron transfer to the C atoms from their Fe nearest neighbours. The C-C interaction was also analysed. For the C-C distance of 1.462Å, there was a bonding between the C atoms. The C-C interaction was stronger than the C-Fe interactions.

The C-C Pair in the Vicinity of a BCC Fe Bulk Vacancy - Electronic Structure and Bonding. S.Simonetti, M.E.Pronsato, G.Brizuela, A.Juan: Physica Status Solidi B, 2006, 244[2], 610-8