  Through detailed comparisons between Embedded Atom Method (EAM) and
first-principles calculations for Al, we find that EAM tends to fail when there
are large electron density gradients present. We attribute the observed
failures to the violation of the uniform density approximation (UDA) underlying
EAM. To remedy the insufficiency of UDA, we propose a gradient-corrected EAM
model which introduces gradient corrections to the embedding function in terms
of exchange-correlation and kinetic energies. Based on the perturbation theory
of "quasiatoms" and density functional theory, the new embedding function
captures the essential physics missing in UDA, and paves the way for developing
more transferable EAM potentials. With Voter-Chen EAM potential as an example,
we show that the gradient corrections can significantly improve the
transferability of the potential.
