Interface dynamics of microscopic cavities in water

An analytical description of the interface motion of a collapsing nanometer-sized spherical cavity in water is presented by a modification of the Rayleigh-Plesset equation in conjunction with explicit solvent molecular dynamics simulations. Quantitative agreement is found between the two approaches for the time-dependent cavity radius R(t) at different solvent conditions while in the continuum picture the solvent viscosity has to be corrected for curvature effects. The typical magnitude of the interface or collapse velocity is found to be given by the ratio of interfacial tension and solvent viscosity, v similar or equal to gamma/eta, while the curvature correction accelerates collapse dynamics on length scales below the equilibrium crossover scales (similar to 1 nm) of hydrophobic solvation. The study offers a starting point for an efficient implicit modeling of water dynamics in aqueous nanoassembly and protein systems in nonequilibrium. (C) 2007 American Institute of Physics.