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Abstract:

The hydrophobic effect of small apolar solutes is studied by molecular dynamic (MD) simulations. Interactions between two solutes can be described by the potential of mean force (PMF). The general feature of the PMF between two solutes in water is a potential barrier separating a stable contact configuration and a meta-stable solvent-separated configuration. Interestingly, compared with classical MD simulation results, a recent study using quantum mechanical MD simulations found a less pronounced potential barrier and a more stable contact potential minimum. We suggest the former is due to the use of hard-core repulsive potentials in MD simulations, while the latter may result from different hydrogen bond network characteristics and the strength of intermolecular interactions between water and solutes. We examined the premise by carrying out classical MD simulations using different functional forms of short-range intermolecular repulsive forces. We also did a more in-depth study of hydrogen-bond network distribution in liquid water to characterize solvation shell structures around hydrophobic solutes. The results elucidate the origin of differences in the PMF between classical force-fields based MD and ab initio MD.


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Next: Introduction Up: Molecular Dynamics Simulations of Previous: Molecular Dynamics Simulations of
Je-Luen Li 2007-07-17