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Full-Text Articles in Engineering

Studies Of A Lattice Model Of Water Confined In A Slit Pore, Peter A. Monson, J. -C. Liu, Frank Van Swol Sep 2007

Studies Of A Lattice Model Of Water Confined In A Slit Pore, Peter A. Monson, J. -C. Liu, Frank Van Swol

Peter A. Monson

We describe an extension of the Bell−Salt lattice model of water to the study of water confined in a slit pore. Wall−fluid interactions are chosen to be qualitatively representative of water interacting with a graphite surface. We have calculated the bulk vapor−liquid phase coexistence for the model through direct Monte Carlo simulations of the vapor−liquid interface. Adsorption and desorption isotherms in the slit pore were calculated using grand canonical ensemble Monte Carlo simulations. In addition, the thermodynamic conditions of vapor−liquid equilibrium for the confined fluid were determined. Our results are consistent with recent calculations for off-lattice models of confined water …


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 Apr 2007

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 Jan 2007

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 …