We investigate the thermally activated glide mobility of dislocations in uranium dioxide (UO₂) from an atomistic point of view using a variable charge many-body empirical potential, the Second Moment Tight-Binding potential with charge equilibration (SMTB-Q). In order to determine the main glide system, we model the dislocation core structures for edge and screw orientations lying in different glide planes. Uncommon core structures with a double periodicity and a charge alternation are obtained. Straight dislocations motion is first considered to obtain the Peierls stress of each dislocation. We then address the thermally activated motion of the dislocations by the nucleation of kink pairs. Atomistic simulations give us the structure as well as the formation and migration energies of kink pairs. This information is finally combined with an elastic interaction model for kink pairs to obtain the dislocation velocities and the evolution of the critical resolved shear stress as a function of temperature. These quantities are compared to experimental data on urania single crystals.

我们研究了二氧化铀（UO ₂）从原子学角度使用可变电荷多体经验电势，即带有电荷平衡的第二矩紧密结合电势（SMTB-Q）。为了确定主要滑行系统，我们对位于不同滑行平面中的边缘和螺钉方向的位错核心结构进行建模。获得具有双周期性和电荷交替的不常见的核结构。首先考虑直位错运动以获得每种位错的Peierls应力。然后，我们通过扭结对的成核来解决位错的热激活运动。原子模拟为我们提供了扭结对的结构以及形成和迁移能。最后，该信息与扭结对的弹性相互作用模型相结合，以获得位错速度和临界分解剪应力随温度的变化。将这些量与关于尿素单晶的实验数据进行比较。