Modeling the effect of backbone instabilities and guest occupancies on interfacial and structural processes and dynamics of sII gas hydrate systems using molecular dynamics

Abstract

Gas hydrates are inclusion compounds that form in conditions of low temperature and high-pressure systems with water and gaseous molecules. Their potential use in carbon capture and storage, energy exploitation, and flue gas extraction makes them prime candidates for various engineering applications and climate change mitigation technologies. However, their nucleation is poorly understood and the effect of guest molecule interactions with the host on macroscale properties has yet to be elucidated. Herein we study the optimal positions of a point mass, linear molecule, and planar triangular guest molecule using a distance minimization technique that can replicate preliminary density functional theory results. The linear molecule shows strong alignment to hexagonal phases of cages, while the triangular guest molecule shows very distinct positions. These positions indicate a lower number of degrees of freedom, which in turn affect the molecules’ ability to move and vibrate in heat absorption, for example. Additionally, it shows that hydrate formation may only be possible when the guest is oriented a certain way, providing an avenue to control nucleation by adjusting guest molecule position with external fields.

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