A mesoscopic model was proposed which explained the discrepancy (by a factor of 2 to 3) between the experimentally measured yield stresses of body-centered cubic metals at low temperatures, and typical Peierls stresses determined by atomistic simulations of isolated screw dislocations. The model involved a Frank-Read-type source emitting dislocations that became pure screws at a certain distance from the source and, due to their high Peierls stress, controlled its operation. Due to the mutual interaction between emitted dislocations, a group which consisted of both non-screw and screw dislocations could move at an applied stress that was a factor of 2 to 3 lower than the stress needed for the glide of individual screw dislocations.

Explanation of the Discrepancy between the Measured and Atomistically Calculated Yield Stresses in Body-Centred Cubic Metals. R.Gröger, V.Vitek: Philosophical Magazine Letters, 2007, 87[2], 113-20