  The embedded atom method (EAM) potentials are probably the most widely used
interatomic potentials for metals and alloys. However, the EAM potentials
impose three constraints on elastic constants that are inconsistent with
experiments. At a more subtle (but more important) level, the EAM potentials
often incorrectly describe the outward/inward relaxation of surface layers, and
therefore will not reliably describe nanostructures. This Letter reports a
response EAM (R-EAM) that addresses both issues. Conceptually, the electron
distribution from each atom does not respond to the atoms environment within
the EAM. In reality, the electron distribution from each atom depends on the
atoms environment, and this dependence is explicitly incorporated in the R-EAM.
Analytical derivation shows that the R-EAM potentials do not impose these three
constraints on elastic constants that EAM potentials do. Further, taking
hexagonal close packed (HCP) metals Ti, Mg, and Zn as the prototypes, the
authors show that the R-EAM potentials correctly describe surfaces, in terms of
interlayer spacing and surface reconstruction, in agreement with quantum
mechanics calculations, while EAM potentials are not in agreement. In
comparison to EAM potentials, the R-EAM potentials require only approximately
twice the computational power.
