Fast generation of reliable primary radiation damage of BCC tungsten by sampling molecular dynamics databases

Fast generation of reliable primary radiation damage plays a key role in modeling of long-term defect evolution in materials under irradiation within the multi-scale modeling framework. We have proposed a model, PradG, to fast generate reliable primary radiation damage by sampling limited molecular dynamics databases. First, MD cascade simulations for body-centered-cubic W are systematically carried out with a wide range of discrete cascade energies. Through introducing the spherical symmetry approximation of cascade volume and analyzing cascade configurations, we find that the size distribution shows a piecewise power-law formula, and the radial distribution shows the Gaussian and exponential decay types for interstitial and vacancy clusters, respectively. Second, by using a sampling method based on these fitting size and spatial distribution, regardless of the spatial correlation of interstitial and vacancy clusters, PradG is developed for generating primary defects of arbitrary cascade energies. Third, the reliability and validation of PradG are verified by comparing with cascade annealing simulations and defect evolution in fission neutron irradiated W. It provides a reliable damage source term for multi-scale modeling of long-term defect evolution with a certain PKA energy spectrum.