The high stochasticity of collision cascades makes running large sets of molecular dynamics simulations mandatory to obtain meaningful statistics. The convergence of the number of defects and of clusters and of the Primary Knock-On Atom (PKA) penetration depth with respect to the number of simulations in the sets is investigated for PKAs of 1 keV and 5 keV in Si. Two methods for setting the initial directions of the PKAs are compared: one is entirely based on randomness and the other integrates symmetry considerations. The latter method eases the convergence of the results. Larger sets are needed to converge the PKA depth than the number of clusters and defects. We observe that the higher the energy of the PKA, the harder it gets to reach the convergence. We find that large sets of simulations enables to get rid of the influence of the initial position of the PKA.

碰撞级联的高度随机性使得必须运行大量的分子动力学模拟以获得有意义的统计数据。对于硅中1 keV和5 keV的PKA，研究了缺陷数量和簇数量以及一次敲击原子（PKA）穿透深度相对于组中模拟数量的收敛性。比较了两种设置PKA初始方向的方法：一种完全基于随机性，另一种则考虑了对称性。后一种方法简化了结果的收敛。收敛PKA深度所需的集要比簇和缺陷的数量大。我们观察到，PKA的能量越高，则达到收敛的难度就越大。