Understanding the Movement, Encapsulation, and Energy Barrier of Water Molecule Diffusion into and in Silicalites Using Ab Initio Calculations

Bussai, C.; Hannongbua, Supot; Haberlandt, R.

doi:10.1021/jp003337w

Cited by 18 publications

(32 citation statements)

References 21 publications

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“…MC steps. As can be seen, equilibration is reached after approximately 2×104 blocks, that is to say around 3×105 trials per water molecule. To acquire data, another 5×10 5 trials per molecule were run, where the number of particles fluctuates around a constant value.…”

mentioning

confidence: 95%

Grand Canonical Monte Carlo Simulation Study of Water Adsorption in Silicalite at 300 K

Puibasset

Pellenq

2008

J. Phys. Chem. B

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This molecular simulation work focuses on the adsorption of water in a priori hydrophobic silicalite-1, a microporous ordered silica. The water-water interactions are described with the SPC model, while water-silica interactions are calculated in the framework of the PN-TrAZ model. The water adsorption isotherm at 300 K, the configurational energies, and the isosteric heat of adsorption are calculated by the grand canonical Monte Carlo (GCMC) simulation method. The thermodynamic integration scheme allows one to calculate the grand potential along the adsorption isotherm. The adsorption results are compared with experiments, showing only qualitative agreement. Indeed, the simulations do not reproduce the expected hydrophobicity of silicalite (Eroshenko, V.; Regis, R.-C.; Soulard, M.; Patarin, J. C. R. Phys. 2002, 3, 111). This indicates that common models used to describe confined polar molecules are far from being operative. In this work, it is shown, on the basis of periodic ab initio calculations, that confined water molecules in silicalite have a dipole value roughly 10% smaller than that in the bulk liquid phase, indicating that the environment felt by a confined water molecule in silicalite pores is not equivalent to that in the bulk liquid. This suggests that effective intermolecular potentials parametrized for bulk water are inefficient to describe ultraconfined water molecules. Reducing the SPC water dipole moment by 5% (i.e., decreasing water partial charges in magnitude) in GCMC calculations does allow reproducing the experimental water/silicalite isotherm at 300 K.

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confidence: 95%

Grand Canonical Monte Carlo Simulation Study of Water Adsorption in Silicalite at 300 K

Puibasset

Pellenq

2008

J. Phys. Chem. B

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“…Molecular simulations is a well suitable to gain a profound understanding of dynamical, structural or thermodynamic properties of polar and non polar fluids confined in nanopores (Auerbach et al 2003;Bussai et al, 2001Bussai et al, , 2002Bussai et al, , 2003Demontis et al 2003;Fleys et al 2004;Desbiens et al 2005;Douguet et al 1996;Fleys and Thompson 2005;Ramachandran et al 2006;Puibasset and Pellenq 2003a).…”

Section: Introductionmentioning

confidence: 99%

Molecular simulations of water in hydrophobic microporous solids

2008

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This work reports Grand Canonical Monte-Carlo molecular simulation (GCMC) results of water adsorption in a priori hydrophobic microporous solids such as silicalite, a purely siliceous zeolite (Ø pore ∼ 5 Å) and C-Y, a pure carbon replica of zeolite Y (Ø pore ∼ 1 nm). At a first step, in both cases, the water-water interactions are described with the SPC model (calibrated for bulk liquid water) while watersubstrate interactions are calculated within the framework of the PN-TrAZ model. This adsorbate-zeolite potential decomposes into short range (repulsive, inductive and dispersive) interaction terms with transferable parameters plus, in the case of silicalite, an electrostatic interaction term based on SPC partial charges for water and ab initio charges for silicalite. With such a standard approach, we found that water fills the microporous volume in both materials at pressure value well below P 0 ; hence does not show a strong hydrophobic behaviour at variance with reference experiments (V. Eroshenko et al. in C. R. Phys. 3:111, 2002). This indicates that common models used to describe confined polar molecules are far from being operative. We show on the basis of periodic ab initio calculations that confined water molecules in silicate have a dipole value ∼10% smaller than that in the 3D liquid phase indicating that the environment felt by a confined water molecule in silicalite pores is not equivalent to that in the bulk liquid. This implies that classical simulations of polar molecules in ultra

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“…One question of interest was wether the water molecules form clusters in the channels of silicalite-1. In the cases investigated in [200][201][202][203][204] no clusters could be found. The diffusion coefficients obtained from the simulations agree satisfactorily with those from experiments [204].…”

Section: Quantum Chemical -Potential Calculations and MD Simulationsmentioning

confidence: 78%

“…Of course, various modifications of these two major routes exist. In a cooperation of theoretical and experimental groups at Leipzig university with scientists at Chulalongkorn University, Bangkok, quantum calculations of potentials have been carried out and the potentials then have been used in MD simulations to investigate the static and dynamic properties of water in silicalite-1 [200][201][202][203][204]. One question of interest was wether the water molecules form clusters in the channels of silicalite-1.…”

Section: Quantum Chemical -Potential Calculations and MD Simulationsmentioning

confidence: 99%

Modeling and Simulation of Structure, Thermodynamics, and Transport of Fluids in Molecular Confinements

Fritzsche¹,

Haberlandt²,

Vörtler³

2004

Molecules in Interaction With Surfaces and Interfaces

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Abstract. The theoretical understanding of the properties of molecular confined fluids is crucial for many applications in science and technology, which reach from molecules enclosed in porous media (zeolites) to aqueous phases at biological active interfaces (biomembranes). We discuss these complicated many-particle systems -which usually are to complex for an analytical statistical-mechanical treatment-by means of molecular simulation methods. We focus on advanced Monte Carlo techniques to study structure and thermodynamics of inhomogeneous fluids and on recent molecular dynamics methods to describe transport phenomena in microporous materials.The state of the art in the field is demonstrated by reviewing selected results of our recent computer simulations. We present both Monte Carlo studies of equilibrium properties of geometrically restricted fluids (such as spatial distribution functions, thermodynamic pressures and phase equilibria) and molecular dynamics studies of dynamical processes in nanoporous media, particularly diffusion of guest molecules in zeolites. The diffusion mechanism is analyzed in detail by computer simulations and theoretical analytical treatment as well.

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Understanding the Movement, Encapsulation, and Energy Barrier of Water Molecule Diffusion into and in Silicalites Using Ab Initio Calculations

Cited by 18 publications

References 21 publications

Grand Canonical Monte Carlo Simulation Study of Water Adsorption in Silicalite at 300 K

Grand Canonical Monte Carlo Simulation Study of Water Adsorption in Silicalite at 300 K

Molecular simulations of water in hydrophobic microporous solids

Modeling and Simulation of Structure, Thermodynamics, and Transport of Fluids in Molecular Confinements

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