Predicting Material Properties of Methane Hydrates with Cubic Crystal Structure Using Molecular Simulations

Molecular simulations are used to calculate energy profiles of the cavities in methane hydrates and to derive thermodynamic material parameters. The aim is to obtain non-measurable material parameters comparatively easily in this way and thus to be able to parameterize material data models more universally.

Abstract

Formation of gas hydrates is an important feature of water systems. It occurs undesirably in natural gas pipelines, but also in deep-sea deposits and unfreezing permafrost. However, the natural occurrence is of particular interest because methane hydrates have one of the highest energy densities of all naturally occurring forms of methane. Therefore, an accurate description of its thermodynamic properties is required. In this work, we demonstrate how the material properties of methane hydrate can be more easily calculated compared to ab initio methods. Furthermore, it is shown how the material properties depend on the cage occupancy by using the comparably fast self-consistent-charge density-functional tight-binding (SCC-DFTB) method. The cell potential is calculated and compared to a numerical as well as an ab initio model, and is in good agreement with the literature.

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