Dislocations are line defects in crystals, and their motion is the carrier for plastic deformation of
crystals under most conditions (T< Tn/2).36,37 The defects produced by irradiation (such as vacancy and interstitial complexes) interact with dislocations, and this interaction is responsible for the change in the mechanical properties by irradiation (such as embrittlement).38 MD simulations of dislocation interaction with other defects are discussed in detail in Chapter 1.12, Atomic-Level Level Dislocation Dynamics in Irradiated Metals. Here, we describe a more basic case study on the mobility of an edge dislocation in Ta. In Section 1.09.6.2.1, we describe the method of computing its Peierls stress, which is the critical stress to move the dislocation at zero temperature. In Section 1.09.6.2.2, we describe how to compute the mobility of this dislocation at finite temperature by MD.