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Citation: L.S.I. Liyanage, S.-G. Kim, J. Houze, S. Kim, M.A. Tschopp, M.I. Baskes, and M.F. Horstemeyer (2014), "Structural, elastic, and thermal properties of cementite (Fe3C) calculated using a modified embedded atom method", Physical Review B, 89(9), 94102. DOI: 10.1103/physrevb.89.094102.
Abstract: Structural, elastic, and thermal properties of cementite (Fe3C) were studied using a modified embedded atom method (MEAM) potential for iron-carbon (Fe-C) alloys. Previously developed Fe and C single-element potentials were used to develop a Fe-C alloy MEAM potential, using a statistics-based optimization scheme to reproduce structural and elastic properties of cementite, the interstitial energies of C in bcc Fe, and heat of formation of Fe-C alloys in L12 and B1 structures. The stability of cementite was investigated by molecular dynamics simulations at high temperatures. The nine single-crystal elastic constants for cementite were obtained by computing total energies for strained cells. Polycrystalline elastic moduli for cementite were calculated from the single-crystal elastic constants of cementite. The formation energies of (001), (010), and (100) surfaces of cementite were also calculated. The melting temperature and the variation of specific heat and volume with respect to temperature were investigated by performing a two-phase (solid/liquid) molecular dynamics simulation of cementite. The predictions of the potential are in good agreement with first-principles calculations and experiments.

LAMMPS pair_style meam (2014--Liyanage-L-S-I--Fe-C--LAMMPS--ipr2)
Notes: These files were contributed by Laalitha Liyanage (Central Michigan Univ., Univ. of North Texas) on 14 Apr. 2014.
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Citation: K.O.E. Henriksson, C. Björkas, and K. Nordlund (2013), "Atomistic simulations of stainless steels: a many-body potential for the Fe-Cr-C system", Journal of Physics: Condensed Matter, 25(44), 445401. DOI: 10.1088/0953-8984/25/44/445401.
Abstract: Stainless steels found in real-world applications usually have some C content in the base Fe–Cr alloy, resulting in hard and dislocation-pinning carbides—Fe3C (cementite) and Cr23C6—being present in the finished steel product. The higher complexity of the steel microstructure has implications, for example, for the elastic properties and the evolution of defects such as Frenkel pairs and dislocations. This makes it necessary to re-evaluate the effects of basic radiation phenomena and not simply to rely on results obtained from purely metallic Fe–Cr alloys. In this report, an analytical interatomic potential parameterization in the Abell–Brenner–Tersoff form for the entire Fe–Cr–C system is presented to enable such calculations. The potential reproduces, for example, the lattice parameter(s), formation energies and elastic properties of the principal Fe and Cr carbides (Fe3C, Fe5C2, Fe7C3, Cr3C2, Cr7C3, Cr23C6), the Fe–Cr mixing energy curve, formation energies of simple C point defects in Fe and Cr, and the martensite lattice anisotropy, with fair to excellent agreement with empirical results. Tests of the predictive power of the potential show, for example, that Fe–Cr nanowires and bulk samples become elastically stiffer with increasing Cr and C concentrations. High-concentration nanowires also fracture at shorter relative elongations than wires made of pure Fe. Also, tests with Fe3C inclusions show that these act as obstacles for edge dislocations moving through otherwise pure Fe.

Notes: Note that this entry only represents the Fe-C subset of interatomic potentials developed and used in this reference.

LAMMPS pair_style tersoff/zbl (2013--Henriksson-K-O-E--Fe-C--LAMMPS--ipr1)
Notes: The Tersoff/ZBL file was contributed by Astrid Gubbels-Elzas and Peter Klaver (Delft University of Technology, Netherlands) and posted with their approval and that of Krister Henriksson (Univ. of Helsinki, Finland) on 9 Jul. 2014. Note that this file only represents the Fe-C subset of interatomic potentials developed and used in this reference.
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EAM tabulated functions
Notes: The following files were contributed by Dr. Henriksson and modified by C. Becker to include the reference and format in the header information. They represent the potential in Equation 7 of the reference, and the columns are r, VZBL, and d/dr (VZBL). They were approved by Dr. Henriksson for posting on 25 Jul. 2014.
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Citation: D.J. Hepburn, and G.J. Ackland (2008), "Metallic-covalent interatomic potential for carbon in iron", Physical Review B, 78(16), 165115. DOI: 10.1103/physrevb.78.165115.
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.

LAMMPS pair_style eam/fs (2008--Hepburn-D-J--Fe-C--LAMMPS--ipr1)
Notes: This file was implemented in the LAMMPS-compatible EAM/FS format by Sebastien Garruchet and posted with the permission of G.J. Ackland on 13 May 2009.
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Date Created: October 5, 2010 | Last updated: October 02, 2018