University of Massachusetts
Dept. of Mechanical
& Industrial Engineering
ELab 208C
160 Governors Drive
Amherst MA 01003
ashwin at engin.umass.edu

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EAM Potentials for the Fe-H system

We developed two new embedded atom (EAM) potentials for hydrogen in BCC iron. The fitting targets (energies and atomic configurations) were generated from density functional theory (DFT) calculations for several equilibrium and non-equilibrium configurations. The Fe parts of the two potentials are taken from Mendelev et al. [Potential 4 in Philos Mag 11, 3977 (2003)] and Ackland et al. [J Phys: Condens Mat 16, S2629 (2004)]. Please see our paper and the erratum for further details.

(NB: These EAM potentials were further modified by Jun Song and Bill Curtin to avoid clustering of H atoms over extended time scales; additional details can be found in their papers. The potential files provided here DO NOT include Song and Curtin's modifications.)

The potential files provided here were compatible with LAMMPS when we last used them (ca. 2010) and appear to have been used quite widely since then. Nevertheless, we do not guarantee compatibility as the LAMMPS code evolves and we cannot support requests for reformatting/modification. All the required parameters are published in our Phys. Rev. B paper and potential files can be generated in any desired format by the user.

Preferred potentials: We recommend using Potential B, which performs slightly better than Potential A in our tests. You must run these with "pairstyle = eam/fs" (see LAMMPS documentation).

Potential A : This is based on Fe Potential 4 from Mendelev et al. [Philos Mag 11, 3977 (2003)] and fit to bulk, vacancy, and surface data from DFT.

Potential B : This is based on the Fe potential from Ackland et al. [J Phys: Condens Mat 16, S2629 (2004)] and fit to bulk, vacancy, and surface data from DFT.

"Bulk-only" potentials: These potentials were fit only to bulk and vacancy DFT data and are slightly better than Potentials A and B in their response to strain fields in bulk environments. However, these do not perform well at surfaces. Use at your own discretion! Also note that you must run these with "pairstyle = eam/alloy" (see LAMMPS documentation).

Potential A' : This is based on Fe Potential 4 from Mendelev et al. [Philos Mag 11, 3977 (2003)] and fit only to bulk and vacancy data from DFT.

Potential B' : This is based on the Fe potential from Ackland et al. [J Phys: Condens Mat 16, S2629 (2004)] and fit only to bulk and vacancy data from DFT.