Statistical study of defects caused by primary knock-on atoms in fcc Cu and bcc W using molecular dynamics

M Warrier and U Bhardwaj and H Hemani and R Schneider and A Mutzke and MC Valsakumar, JOURNAL OF NUCLEAR MATERIALS, 467, 457-464 (2015).

DOI: 10.1016/j.jnucmat.2015.09.025

We report on molecular Dynamics (MD) simulations carried out in fcc Cu and bccWusing the Large-scale Atomic/Molecular Massively Parallel Simulator (LAMMPS) code to study (i) the statistical variations in the number of interstitials and vacancies produced by energetic primary knock-on atoms (PKA) (0.1-5 keV) directed in random directions and (ii) the in-cascade cluster size distributions. It is seen that around 60e80 random directions have to be explored for the average number of displaced atoms to become steady in the case of fcc Cu, whereas for bcc W around 50e60 random directions need to be explored. The number of Frenkel pairs produced in the MD simulations are compared with that from the Binary Collision Approximation Monte Carlo (BCA-MC) code SDTRIM-SP and the results from the NRT model. It is seen that a proper choice of the damage energy, i.e. the energy required to create a stable interstitial, is essential for the BCA-MC results to match the MD results. On the computational front it is seen that in-situ processing saves the need to input/output (I/O) atomic position data of several terabytes when exploring a large number of random directions and there is no difference in run-time because the extra run-time in processing data is offset by the time saved in I/O. (C) 2015 Elsevier B.V. All rights reserved.

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