Place: DPG Spring Meeting 2011, Dresden, Germany
A coherent transferable tight-binding (TB) parameterization of charge transfer and electronic potentials has yet to be developed for the Fe-C interaction. Additionally, while interatomic potentials have been obtained for this interaction, recent findings show that the results from these potentials are inconsistent with DFT calculations and do not give an accurate portrayal of chemical bonding in the system. Using dual DFT grid and LCAO calculations within GPAW, we obtain one electron wave functions expanded in a multiple- LCAO basis. This is down-folded onto a optimal minimal basis, giving a continuous and transferable description of Fe-C bonding. By constructing a TB energy functional using these bond integrals and a parameterized interatomic repulsion, we show how an accurate description of the energy hierarchy of relevant Fe-C structures, including the interstitial occupancy of carbon in iron, can be achieved. This simple model based on physical insights may be used to study systems containing thousands of atoms.