Role of attractive methane-water interactions in the potential of mean force between methane molecules in water

Abstract

On the basis of a gaussian quasi-chemical model of hydration, a model of non van der Waals character, we explore the role of attractive methane-water interactions in the hydration of methane and in the potential of mean force between two methane molecules in water. We find that the hydration of methane is dominated by packing and a mean-field energetic contribution. Contributions beyond the mean-field term are unimportant in the hydration phenomena for a hydrophobic solute such as methane. Attractive solute-water interactions make a net repulsive contribution to these pair potentials of mean force. With no conditioning, the observed distributions of binding energies are super-gaussian and can be effectively modeled by a Gumbel (extreme value) distribution. This further supports the view that the characteristic form of the unconditioned distribution in the high-e tail is due to energetic interactions with a small number of molecules. Generalized extreme value distributions also effectively model the results with minimal conditioning, but in those cases the distributions are sufficiently narrow that details of their shape aren't significant.

arXiv comment8 pages, 4 figures

References in corpus (6)

• Molecular Theory of Hydrophobic Effects: ``She is too mean to have her name repeated.''
• Temperature Dependence of the Hydrophobic Hydration and Interaction of Simple Solutes: An Examination of Five Popular Water Models
• Connecting local structure to interface formation: a molecular scale van der Waals theory of nonuniform liquids
• Balancing Local Order and Long-Ranged Interactions in the Molecular Theory of Liquid Water
• Role of fluctuations in a snug-fit mechanism of KcsA channel selectivity
• Different thermodynamic pathways to the solvation free energy of a spherical cavity in a hard sphere fluid

Cited by in corpus (10)

• Efficient molecular density functional theory using generalized spherical harmonics expansions
• McMillan-Mayer Theory of Solutions Revisited: Simplifications and Extensions
• Thermodynamics of water modeled using ab initio simulations
• Quasi-chemical theory with a soft cutoff
• Modeling molecular and ionic absolute solvation free energies with quasi-chemical theory bounds
• Water coordination structures and the excess free energy of the liquid
• Molecular packing and chemical association in liquid water simulated using ab initio hybrid Monte Carlo and different exchange-correlation functionals
• Electrostatic and induction effects in the solubility of water in alkanes
• Quasichemical theory and the description of associating fluids relative to a reference: Multiple bonding of a single site solute
• Direct observation of a hydrophobic bond in loop-closure of a capped (-OCH2CH2-)n oligomer in water