Characterization and quantification of numerical errors in threshold displacement energy calculated by molecular dynamics in bcc-Fe (original) (raw)
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Molecular Dynamics (MD) is a very powerful tool for studying displacement cascades initiated by the neutrons when they interact with matter and thus evaluate the primary damage. The mean number of point defects created can be obtained with a fair standard error with a reasonable number of cascade simulations (10 to 20 [1]), however other cascades characteristics (spatial distribution, size and amount of defect clusters ...) display a huge variability. Therefore, they may need to be studied using faster methods such as the Binary Collision Approximation (BCA) which is several order of magnitude less time consuming. We have investigated the point defect distributions subsequent to atomic collision cascades by both MD (using EAM potentials for Fe) and its BCA. MD and its BCA lead to comparable point defect predictions. The significant similarities and differences are discussed.
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Molecular dynamics (MD) is a powerful tool to study the displacement cascades initiated by the neutrons when they interact with matter. Key components of this technique are the interatomic potentials which model the binding of the dierent constitutive atoms. There exist many interatomic potentials dedicated to a-Fe and we have tested three of them for the study of radiation damage. We have found that the primary damage is potential sensitive. From our study, it appears that some characteristics of the potentials, not always considered, can be correlated to the type of damage produced by displacement cascades. The repulsive part of the potential has a strong in¯uence on the cascade morphology. Moreover, equilibrium properties such as the atoms mean square displacements, the vacancy migration and vacancy±vacancy binding energies also appear to have some in¯uence and should be investigated carefully when simulating radiation damage. It is therefore very important to use extreme care when trying to obtain quantitative results from MD simulations. Ó
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