A Hotspots Better Half: Non-Equilibrium Intra-Molecular Strain in Shock Physics

TL;DR

This paper reveals that shock-induced hotspots in materials are primarily due to intra-molecular strains storing potential energy, which persists beyond thermal diffusion and influences chemical reactions.

Contribution

It introduces a molecular dynamics perspective showing potential energy localization in hotspots, highlighting intra-molecular strain as a key factor beyond temperature-based descriptions.

Findings

Potential energy hotspots exceed temperature-based energy estimates.

Intra-molecular strains store significant energy in molecular crystals.

PE hotspots persist despite thermal diffusion.

Abstract

Shockwave interactions with material microstructure localizes energy into hotspots, which act as nucleation sites for complex processes such as phase transformations and chemical reactions. To date, hotspots have been described via their temperature fields. Nonreactive, all-atom molecular dynamics simulations of shock-induced pore collapse in a molecular crystal show that more energy is localized as potential energy (PE) than can be inferred from the temperature field and that PE localization persists through thermal diffusion. The origin of the PE hotspot is traced to large intra-molecular strains, storing energy in modes readily available for chemical decomposition.