Li Yong Gang, Yang Yang, Short Michael P, Ding Ze Jun, Zeng Zhi, Li Ju
Key Laboratory for Materials Physics, Institute of Solid State Physics, Chinese Academy of Sciences, Hefei, 230031, China.
Department of Nuclear Science and Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts, 02139, USA.
Sci Rep. 2015 Dec 11;5:18130. doi: 10.1038/srep18130.
SRIM-like codes have limitations in describing general 3D geometries, for modeling radiation displacements and damage in nanostructured materials. A universal, computationally efficient and massively parallel 3D Monte Carlo code, IM3D, has been developed with excellent parallel scaling performance. IM3D is based on fast indexing of scattering integrals and the SRIM stopping power database, and allows the user a choice of Constructive Solid Geometry (CSG) or Finite Element Triangle Mesh (FETM) method for constructing 3D shapes and microstructures. For 2D films and multilayers, IM3D perfectly reproduces SRIM results, and can be ∼10(2) times faster in serial execution and > 10(4) times faster using parallel computation. For 3D problems, it provides a fast approach for analyzing the spatial distributions of primary displacements and defect generation under ion irradiation. Herein we also provide a detailed discussion of our open-source collision cascade physics engine, revealing the true meaning and limitations of the "Quick Kinchin-Pease" and "Full Cascades" options. The issues of femtosecond to picosecond timescales in defining displacement versus damage, the limitation of the displacements per atom (DPA) unit in quantifying radiation damage (such as inadequacy in quantifying degree of chemical mixing), are discussed.
类似SRIM的代码在描述一般三维几何结构以及模拟纳米结构材料中的辐射位移和损伤方面存在局限性。已开发出一种通用、计算高效且大规模并行的三维蒙特卡罗代码IM3D，它具有出色的并行缩放性能。IM3D基于散射积分的快速索引和SRIM阻止本领数据库，并允许用户选择建设性实体几何（CSG）或有限元三角形网格（FETM）方法来构建三维形状和微观结构。对于二维薄膜和多层膜，IM3D能完美重现SRIM结果，并且在串行执行时速度可快约10²倍，使用并行计算时速度可快>10⁴倍。对于三维问题，它提供了一种快速方法来分析离子辐照下初级位移的空间分布和缺陷产生情况。在此我们还对我们的开源碰撞级联物理引擎进行了详细讨论，揭示了“快速金钦 - 皮斯”和“完整级联”选项的真正含义和局限性。讨论了在定义位移与损伤时飞秒到皮秒时间尺度的问题，以及每个原子位移（DPA）单位在量化辐射损伤方面的局限性（如在量化化学混合程度方面的不足）。
