Atomistic computations of the Peierls stress in fcc metals are relatively
scarce. By way of contrast, there are many more atomistic computations for bcc
metals, as well as mixed discrete-continuum computations of the Peierls-Nabarro
type for fcc metals. One of the reasons for this is the low Peierls stresses in
fcc metals. Because atomistic computations of the Peierls stress take place in
finite simulation cells, image forces caused by boundaries must either be
relaxed or corrected for if system size independent results are to be obtained.
One of the approaches that has been developed for treating such boundary forces
is by computing them directly and subsequently subtracting their effects, as
developed by V. B. Shenoy and R. Phillips [Phil. Mag. A, 76 (1997) 367]. That
work was primarily analytic, and limited to screw dislocations and special
symmetric geometries. We extend that work to edge and mixed dislocations, and
to arbitrary two-dimensional geometries, through a numerical finite element
computation. We also describe a method for estimating the boundary forces
directly on the basis of atomistic calculations. We apply these methods to the
numerical measurement of the Peierls stress and lattice resistance curves for a
model aluminum (fcc) system using an embedded-atom potential.Comment: LaTeX 47 pages including 20 figure