Summary Statements for Hydrate Structure

On the basis of the analyses presented in Section 2.1, the following statements represent a summary of hydrate structures  

Natural gas clathrate hydrates normally form either in the primitive cubic structure I, in the face-centered cubic structure II, or in the hexagonal structure H. 

The hydrogen bond is the basis for the interactions of the water molecules bonding in tetrahedral structures similar to that of ice. Pentagonal and hexagonal water clusters formed by hydrogen bonds are frequently found in water, square clusters exist at less frequent intervals. 

Spaces between the 512 cavities are the larger, oblate 51262 cavities in structure I, or the spherical 51264 cavities in structure II. In structure H, both large (51268) and small (435663) cavities form between layers of 512 cavities. 

Small molecules that occupy the small cavities, also occupy the large cavities. Large molecules can stabilize si or sll by only occupying the large cavity, leaving the smaller cavity vacant. Structure H requires that both large and small cavities be occupied. 

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