The mobility of dislocations is an important factor in understanding material strength. Dislocations experience a drag due to their interaction with the crystal structure, the dominating contribution at high stress and temperature being the scattering off phonons due to phonon wind. Yet, the functional dependence of this effect on velocity and other properties has eluded a good theoretical understanding.
In this talk we present recent results on dislocation drag from first principles as a function of velocity (resp. stress), temperature, density, and character. We then discuss the impact this newly derived drag coefficient has on the overall material response by presenting selected examples from single crystal plasticity simulations as well as an analytical model of stress as a function of strain rate which takes into account mobile-immobile dislocation intersections as well as dislocation drag from phonon wind.