Statistical analysis of a library of molecular dynamics cascade simulations in iron at 100 K

An extensive database of atomic displacement cascades in iron has been developed using molecular dynamics (MD) simulations. Simulations have been carried out at temperatures of 100, 600, and 900 K, and at energies between 0.10 and 50 keV. The results presented here focus on the simulations conducted at 100 K. A sufficient number of cascades has been completed under each condition of cascade energy and temperature to obtain statistically significant average values for the primary damage production parameters. The statistical analysis has been used to examine the influence of primary knockon direction, simulation cell-size, and lattice heating by the high energy recoil. A surprising effect of primary knockon atom (PKA) direction was observed up to 1 keV, but little effect of lattice heating was detected. We have previously reported preliminary results indicating that the ratio of surviving point defects to the number calculated by the Norgett–Robinson–Torrens (NRT) displacement model appears to pass through a minimum value of about 20 keV. The present analysis supports the statistical significance of this minimum, which can be attributed to the onset of extensive subcascade formation.