Computational study on the structure II clathrate hydrate of methane and large guest molecules

H Erfan-Niya and H Modarress and E Zaminpayma, JOURNAL OF INCLUSION PHENOMENA AND MACROCYCLIC CHEMISTRY, 70, 227-239 (2011).

DOI: 10.1007/s10847-010-9899-9

Molecular dynamics (MD) simulations of structure II clathrate hydrates are performed under isobaric-isothermal (NPT) ensembles in a 2 x 2 x 2 structure II unit cell replica with 1,088 TIP4P water molecules to study two main aims: firstly, the effects of methane and large guest molecules (LGMs) on the stability of clathrate hydrate structure and secondly, to study the effects of LGMs on methane storage capacity. The studied LGMs are propane, n-butane, tetrahydrofuran (THF), 1,3-dioxane, 1,4-dioxane, allene, benzene, cyclohexane and neopentane. At the first part of this work, the dynamics of structure II clathrate hydrate is studied to clarify the effects of guest molecules on host lattice structure. The radial distribution functions (RDFs) analysis is used to understand the structure configuration. Then, MD simulations are performed to evaluate the effects of LGMs on methane-storage capacity of the structure II clathrate hydrates at temperature 278 K and as a function of pressures up to 1,000 MPa.

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