Clathrate hydrates guest molecules encaged

Here, we examine the origin of unusually large thermal expansivity of xenon clathrate hydrate (structure I). Xenon interaction is described by an LJ potential whose parameters are given in Table 3[25]. The method is similar to the calculation for ice. The densities of state of water molecules for occupied and empty hydrates are shown in Figure 21. Clearly, frequencies of some modes shift to higher side upon encaging guest molecules. 

Clathrate hydrates form when small (<0.9 nm) non-polar molecules contact water at ambient temperatures (typically <3(X) K) and moderate pressures (typically >0.6 MPa). On a molecular scale, single small guest molecules are encaged (enclathrated) by hydrogen-bonded water cavities in these non-stoichiometric hydrates. Guest repulsions prop open different sizes of water cages, which combine to form three well-defined unit crystals shown in Figure 1. 

Gas clathrate hydrates (also known as gas hydrates) are crystalline inclusion compounds composed of hydrogen-bonded water cavities (host) which encage small gas (guest) molecules. Generally, a maximum of one guest molecule occupies each water cavity. Typical guest molecules that form gas hydrates are meth-... 

Next, the free energy is calculated for the clathrate hydrate encaging spherical guest according to Eq. (71). The free energy containing nonspherical molecules is calculated by adding the contribution from Eq. (72) as... 

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