  Understanding plastic deformation of crystals in terms of the fundamental
physics of dislocations has remained a grand challenge in materials science for
decades. To overcome this, the Discrete Dislocation Dynamics (DDD) method has
been developed, but its lack of atomistic resolution leaves open the
possibility that certain key mechanisms may be overlooked. By comparing
large-scale Molecular Dynamics (MD) with DDD simulations performed under
identical conditions we uncover significant discrepancies in the predicted
strength and microstructure evolution in BCC crytals under high-strain rate
conditions. These are traced to unexpected behaviors of dislocation network
nodes forming at dislocation intersections, that can move in ways not
previously anticipated as revealed by MD. Once these newfound freedoms of nodal
motion are incorporated, DDD simulations begin to closely match plastic
evolution observed in MD. This additional mechanism of motion whereby non-screw
dislocations can change their glide plane profoundly affects fundamental
processes of dislocation multiplication, recovery and storage that define
strength of metals.
