Metallic-covalent interatomic potential for carbon in iron
Abstract
Existing interatomic potentials for the iron-carbon system suffer from qualitative flaws in describing even the simplest of defects. In contrast to more accurate first-principles calculations, all previous potentials show strong bonding of carbon to overcoordinated defects (e.g., self-interstitials, dislocation cores) and a failure to accurately reproduce the energetics of carbon-vacancy complexes. Thus any results from their application in molecular dynamics to more complex environments are unreliable. The problem arises from a fundamental error in potential design—the failure to describe short-ranged covalent bonding of the carbon p electrons. We describe a resolution to the problem and present an empirical potential based on insights from density-functional theory, showing covalent-type bonding for carbon. The potential correctly describes the interaction of carbon and iron across a wide range of defect environments. It has the embedded atom method form and hence appropriate for billion atom molecular-dynamics simulations.
- Publication:
-
Physical Review B
- Pub Date:
- October 2008
- DOI:
- 10.1103/PhysRevB.78.165115
- Bibcode:
- 2008PhRvB..78p5115H
- Keywords:
-
- 61.50.Ah;
- 31.15.xv;
- 61.72.J-;
- 61.82.Bg;
- Theory of crystal structure crystal symmetry;
- calculations and modeling;
- Molecular dynamics and other numerical methods;
- Point defects and defect clusters;
- Metals and alloys