Impact of Short-Range Forces on Defect Production from High Energy Collisions

RE Stoller and A Tamm and LK Beland and GD Samolyuk and GM Stocks and A Caro and LV Slipchenko and YN Osetsky and A Aabloo and M Klintenberg and Y Wang, JOURNAL OF CHEMICAL THEORY AND COMPUTATION, 12, 2871-2879 (2016).

DOI: 10.1021/acs.jctc.5b01194

Primary radiation damage formation in solid materials typically involves collisions between atoms that have up to a few hundred keV of kinetic energy. Dining these collisions, the-distance between two colliding atoms can approach 0.05 nm. At such small atomic separations, force fields fitted-to equilibrium properties tend to significantly underestimate the potential-energy-of the colliding dieter. To enable molecular dynamics simulations of high-energy collisions, it is common practice to use a screened Coulomb, force field to describe the interactions and to smoothly join this to the equilibrium force field at a suitable interatomic spacing. However, there is,no accepted standard method for choosing the parameters used in the joining process, and our results prove that defect production is sensitive to how the force field's are linked. A new procedure is presented that involves the use of ab initio calculations to,determine the magnitude and spatial dependence of the pair interactions at intermediate distances, along with systematic criteria for choosing the joining parameters. Results are presented for the case of nickel, which demonstrate the use and validity of the procedure.

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