Atomistic material behavior at extreme pressures

LK Beland and YN Osetsky and RE Stoller, NPJ COMPUTATIONAL MATERIALS, 2, 16007 (2016).

DOI: 10.1038/npjcompumats.2016.7

Computer simulations are routinely performed to model the response of materials to extreme environments, such as neutron (or ion) irradiation. The latter involves high-energy collisions from which a recoiling atom creates a so-called atomic displacement cascade. These cascades involve coordinated motion of atoms in the form of supersonic shockwaves. These shockwaves are characterized by local atomic pressures > 15 GPa and interatomic distances < 2 angstrom. Similar pressures and interatomic distances are observed in other extreme environment, including short- pulse laser ablation, high-impact ballistic collisions and diamond anvil cells. Displacement cascade simulations using four different force fields, with initial kinetic energies ranging from 1 to 40 keV, show that there is a direct relationship between these high-pressure states and stable defect production. An important shortcoming in the modeling of interatomic interactions at these short distances, which in turn determines final defect production, is brought to light.

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