PNNL

Abstract

Hydrate networks are ‘host’ lattices for the storage of ‘guest’ natural gases. To enhance their physical stabilities near ambient conditions, the most stable clathrate hydrates should be identified. Here, we report the lowest energy networks of the tetrakaidecahedral cage (T-cage) (H2O)24 cluster, a constituent of the cubic unit cell of the structure I (sI) hydrate. A four-step screening method was employed to search for the lowest T-cage networks, which were eventually optimized at the MP2 level of theory. The obtained low-energy isomers can furthermore be used to obtain the low-energy hydrogen bonding networks of periodic structures of hydrates thus allowing for the realistic modeling of the accommodation of ‘guest’ molecules in clathrate hydrates. This work was supported by the US Department of Energy's Office of Basic Energy Sciences, Chemical Sciences program. Pacific Northwest National Laboratory is operated by Battelle for DOE.