A molecular dynamics simulation study of thermal transport in hydrazinium cyclo-pentazolate

Abstract

Cyclo-pentazolate salts (CPSs) as a new type of high-energy-density materials (HEDMs) with high nitrogen content have attracted considerable research attention. In contrast to the extensive studies on their energy properties, the thermal transport process in CPSs has been less studied which relates closely to the thermal safety of this material. Concerning the hydrazinium cyclo-pentazolate (HCP), we conduct a computational study to estimate the thermal conductivity of HCP by means of the non-equilibrium molecular dynamics (NEMD) simulation. To achieve that, we have customized interaction parameters based on the default OPLS force field for the HCP, as benchmarked by its crystal structure. Our simulations have revealed surprisingly anisotropic thermal conductivity for the HCP, while the thermal conductivity becomes highest roughly in the direction perpendicular to cyclo-N5 - with its value notably higher than common high explosives. By modulating the interaction parameters within the HCP molecule, we have further captured a dominant role of the interaction between cyclo-N5 - in regulating the thermal conductivity of the HCP. The attractive Lennard-Jones (LJ) potential may restrict the relative motion between cyclo-N5 -, which forms a long-range order thus enhances thermal transport in the direction perpendicular to cyclo-N5 -. Our simulation result on the effect of (cyclo-N5 -)-(cyclo-N5 -) interaction provide insights to engineer thermal transport in CPSs at the molecular level.