Structure and stability of Fe4C bulk and surfaces: A density functional theory study

Density functional theory calculations identify the Fe4C structure with octahedral interstitial carbon (Fe4C/oct) to be more stable than that with tetrahedral interstitial carbon (Fe4C/tet). The most stable termination of Fe4C/oct is the (1 0 0) surface with interstitial carbon and iron, and that of Fe4C/tet is the (1 1 0) reconstructed surface with surface iron and carbon.