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MEAM

MEAM: Modified Embedded Atom Method
Definition:A method to approximate the total energy of a random arrangement of atoms.
Explanation:As in embedded atom method (→EAM), the energy of atomic arrangement is given by a sum of electrostatic pair terms and an embedding function which describes the local energy density. Equivalent to density functional theory (→DFT), MEAM describes the system as a function of electron density, but uses the approximation that the density of the whole system is a simple superposition of the local atomic densities.

In addition to EAM, an explicit three body term is included to improve the potentials description of materials with highly directional bonds. This also indirectly implies a range of the potential including the next nearest atom neighbors, which may improve accuracy, but increases calculation time. MEAM is three to five times slower than EAM.

The total energy form for the MEAM potential is given in the equation below, where φij(rij) is the pair potential term describing electrostatic core-core repulsion, and the cohesive term, Fi(ni), describes the energy gain of the ion core when it is embedded in the energy density, ni, which is the superposition of the local energy densities ρj(rij) and the three body term. The three body term influences the electron density through the dependence of fij(rij) and gi(cosθjik).
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Diagram:


Gamma-surface of an Al MEAM potential.
SFB-Link:The MEAM is used in molecular dynamics (→MD) simulations in part project A6 to determine grain boundary mobility.
References:Baskes, Phys Rev B, 46, 2727-2742, 1992