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Further Studies Of A Simple Atomistic Model Of Silica: Thermodynamic Stability Of Zeolite Frameworks As Silica Polymorphs, Peter A. Monson, S. M. Auerbach, M. H. Ford
Further Studies Of A Simple Atomistic Model Of Silica: Thermodynamic Stability Of Zeolite Frameworks As Silica Polymorphs, Peter A. Monson, S. M. Auerbach, M. H. Ford
Peter A. Monson
We have applied our previously reported model of silica based on low coordination and strong association [ J. Chem. Phys. 121, 8415 (2004) ], to the calculation of phase stability of zeolite frameworks SOD, LTA, MFI, and FAU as silica polymorphs. We applied the method of Frenkel and Ladd for calculating free energies of these solids. Our model predicts that the MFI framework structure has a regime of thermodynamic stability at low pressures and above ∼ 1400 K, relative to dense phases such as quartz. In contrast, our calculations predict that the less dense frameworks SOD, LTA, and FAU exhibit …
Calculation Of Free Energies And Chemical Potentials For Gas Hydrates Using Monte Carlo Simulations, Peter A. Monson, S. J. Wierzchowski
Calculation Of Free Energies And Chemical Potentials For Gas Hydrates Using Monte Carlo Simulations, Peter A. Monson, S. J. Wierzchowski
Peter A. Monson
We describe a method for calculating free energies and chemical potentials for molecular models of gas hydrate systems using Monte Carlo simulations. The method has two components: (i) thermodynamic integration to obtain the water and guest molecule chemical potentials as functions of the hydrate occupancy; (ii) calculation of the free energy of the zero-occupancy hydrate system using thermodynamic integration from an Einstein crystal reference state. The approach is applicable to any classical molecular model of a hydrate. We illustrate the methodology with an application to the structure-I methane hydrate using two molecular models. Results from the method are also used …