Thermodynamic stability of clathrate hydrates

H. Tanaka and K. Kiyohara, The thermodynamic stability of clathrate hydrate. II. Simultaneous occupation of larger and smaller cages , J. Chem. Phys. 98 (1993) 8110. 

STATISTICAL MECHANICAL APPROACH TO THE THERMODYNAMIC STABILITY OF CLATHRATE HYDRATES... 

VII. Application to Thermodynamic Stability of Clathrate Hydrates A. Chemical Potential of Ices and Empty Clathrate Hydrates... 

The chemical potential difference is tabulated in Table III [17,18]. There are small but nonmegligible differences depending on both the method and the pair potential. Two distinctive features are noteworthy. CS-II is more stable than CS-I irrelevant as to whether the anharmonic free energy is taken into account for the TIP4P potential (all the properties are calculated for clathrate hydrates with this potential unless otherwise mentioned) [52]. This is also true for most of the other pair potential of water such as SPC/E [53]. The chemical potential difference is negative for most of the potential but it is positive for the CC potential [54] and other potentials with the same functional form, which is favorable to observe a hydration structure around a hydrophobic solute but is inappropriate to evaluate the thermodynamic stability of clathrate hydrates. 

It is highly desirable to establish a relationship between reduction of the dissociation pressure and the efficiency as hydrogen storage in a wide range of pressure with varying composition of a promoter species. To this end, we should find a simple way to evaluate the thermodynamic stability of clathrate hydrates and its cage occupancy from intermolecular interactions currently available under a fixed occupancy of a promoter guest elaborated in Section III.D. Since the chemical potential of water is written as... 

H. Tanaka,/. Chem. Phys., 101, 10833 (1994). The Thermodynamic Stability of Clathrate Hydrate. III. Accommodation of Nonspherical Propane and Ethane Molecules. 

H. Tanaka and M. Matsumoto,/. Phys. Chem. B, 115, 14256 (2011). On the Thermodynamic Stability of Clathrate Hydrates V Phase Behaviors Accommodating Large Guest Molecules with New Reference States. 

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