  The stress-driven motion of dislocations in crystalline solids, and thus the
ensuing plastic deformation process, is greatly influenced by the presence or
absence of various point-like defects such as precipitates or solute atoms.
These defects act as obstacles for dislocation motion and hence affect the
mechanical properties of the material. Here we combine molecular dynamics
studies with three-dimensional discrete dislocation dynamics simulations in
order to model the interaction between different kinds of precipitates and a
$\frac{1}{2}\langle 1 1 1\rangle$ $\{1 1 0\}$ edge dislocation in BCC iron. We
have implemented immobile spherical precipitates into the ParaDis discrete
dislocation dynamics code, with the dislocations interacting with the
precipitates via a Gaussian potential, generating a normal force acting on the
dislocation segments. The parameters used in the discrete dislocation dynamics
simulations for the precipitate potential, the dislocation mobility, shear
modulus and dislocation core energy are obtained from molecular dynamics
simulations. We compare the critical stresses needed to unpin the dislocation
from the precipitate in molecular dynamics and discrete dislocation dynamics
simulations in order to fit the two methods together, and discuss the variety
of the relevant pinning/depinning mechanisms.
