Gas hydrate nucleation and cage formation at a water/methane interface.

Nucleation of gas hydrates remains a poorly understood phenomenon, despite its importance as a critical step in understanding the performance and mode of action of low dosage hydrate inhibitors. We present here a detailed analysis of the structural and mechanistic processes by which gas hydrates nucleate in a molecular dynamics simulation of dissolved methane at a methane/water interface. It was found that hydrate initially nucleates into a phase consistent with none of the common bulk crystal structures, but containing structural units of all of them. The process of water cage formation has been found to correlate strongly with the collective arrangement of methane molecules.