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Embedded atom model

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In computational chemistry and computational physics, the embedded atom model, embedded-atom method or EAM, is an approximation describing the energy between atoms and is a type of interatomic potential. The energy is a function of a sum of functions of the separation between an atom and its neighbors. In the original model, by Murray Daw and Mike Baskes,[1] the latter functions represent the electron density. The EAM is related to the second moment approximation to tight binding theory, also known as the Finnis-Sinclair model. These models are particularly appropriate for metallic systems.[2] Embedded-atom methods are widely used in molecular dynamics simulations.

Model simulation

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In a simulation, the potential energy of an atom, , is given by[3]

,

where is the distance between atoms and , is a pair-wise potential function, is the contribution to the electron charge density from atom of type at the location of atom , and is an embedding function that represents the energy required to place atom of type into the electron cloud.

Since the electron cloud density is a summation over many atoms, usually limited by a cutoff radius, the EAM potential is a multibody potential. For a single element system of atoms, three scalar functions must be specified: the embedding function, a pair-wise interaction, and an electron cloud contribution function. For a binary alloy, the EAM potential requires seven functions: three pair-wise interactions (A-A, A-B, B-B), two embedding functions, and two electron cloud contribution functions. Generally these functions are provided in a tabularized format and interpolated by cubic splines.

See also

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References

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  1. ^ Daw, Murray S.; Mike Baskes (1984). "Embedded-atom method: Derivation and application to impurities, surfaces, and other defects in metals". Physical Review B. 29 (12). American Physical Society: 6443–6453. Bibcode:1984PhRvB..29.6443D. doi:10.1103/PhysRevB.29.6443.
  2. ^ Daw, Murray S.; Foiles, Stephen M.; Baskes, Michael I. (1993). "The embedded-atom method: a review of theory and applications". Mat. Sci. Eng. Rep. 9 (7–8): 251. doi:10.1016/0920-2307(93)90001-U.
  3. ^ "Pair - EAM". LAMMPS Molecular Dynamics Simulator. Retrieved 2008-10-01.