A study of vapor-liquid equilibria of polarizable fluids by Monte Carlo simulation

In this work, we discuss the modeling of vapor-liquid coexistence properties for polarizable molecules. In particular, we focus on polarizable Stockmayer fluids and polarizable water models. Efficient methodologies of these fluids for Monte a Carlo simulations and data analysis are developed for calculation of coexistence properties.; Simulation techniques have been developed for free energy calculation between different potential models, or thermodynamic states. Among them is Valleau's thermodynamic scaling Monte Carlo concept that makes use of a non-Boltzmann distribution for the sampling of configurational space relevant to a range of potential models, or thermodynamic states. We combine the thermodynamic scaling Monte Carlo concept with the Gibbs ensemble method for phase coexistence calculations. Using the combined method, phase coexistence properties of several Hamiltonians (potential models) at many temperatures are obtained in a single simulation. An application to the (n-6) Lennard-Jones family of potentials is demonstrated. The combined method is found to be more efficient than conventional Gibbs ensemble method for properties of related potential models at many thermodynamic states.; The phase coexistence properties of polarizable Stockmayer fluids of reduced permanent dipoles {dollar}rmvert msp*sb0vert{dollar} = 1.0 and 2.0 and reduced polarizabilities {dollar}rmalphasp*=0.00, 0.03, and 0.06{dollar} are calculated by a series of grand canonical Monte Carlo simulations with the histogram reweighting method proposed by Ferrenberg and Swendsen. The results are compared with Wertheim's renormalization perturbation theory. Deviations between theory and simulation results for the coexistence envelope are near 2% for the lower dipole moment and 10% for the higher dipole moment we studied.; We calculate the vapor-liquid coexistence densities of polarizable water models near the critical point by a series of grand canonical Monte Carlo simulations with the histogram reweighting method. We introduce polarizability on point charge water models in order to account for the three-body and higher interaction explicitly. Significant effects of polarizability are observed in coexistence density, vapor pressure and heat of vaporization. However, the models we used showed large deviations for the coexistence properties from the experimental values. Some attempts are made to fit the potential parameters to reproduce the experimental values for the coexistence properties.