The solvation and hydrophobic interaction of non-polar molecules in water in the approximation of interatomic potentials: The Monte Carlo method

Abstract

The problem of calculating thermodynamic functions of solvation and hydrophobic interaction of non-polar molecules in water is considered, and the functions of ‘switched off’ interaction which allow one to compare calculated and experimental data are introduced and discussed. Expressions for the free energies, entropies and internal energies of solvation and hydrophobic interaction are deduced by statistical mechanics, and the possibility of computing these quantities from information about interatomic potential functions is considered. An application of the Monte Carlo method with the Boltzmann transition probabilities between the states of a Markov chain has allowed us to evaluate configuration integrals and thermodynamic functions of solvation and hydrophobic interaction. For solvation, the calculated values are in good agreement with the experimental data if the periodic boundary conditions are observed, and in moderate agreement should these be neglected. For hydrophobic interaction, the plot of F _HI(R ₁₂) is built and the potentials of average force for two methane molecules, as well as two hard spheres, is evaluated.