Structures of Liquid Iron-Light-Element Mixtures under High Pressure

The effects of light elements such as H, C, O, Si, and S on the local structures of liquid Fe under high pressure are investigated by ab initio molecular dynamics (MD) simulations. The simulations clarify that H, C, and O are incorporated into liquid Fe interstitially while Si and S are "substitutional" type impurities. From the calculated partial pair distribution functions, it is found that an interaction between light elements exists even under high-pressure conditions exceeding 100 GPa. Additionally, the interaction depends on the type of element. The C-C interactions are stronger than those of other light elements. The S-S interactions depend on the S concentration, in the sense that the shape of pair distribution functions for the S-S correlation changes with increasing S concentration.