Correlated dynamics of water and amphiphilic molecules in thin Newton black films

The dynamical properties of amphiphilics in Newton black films, as well as those of the water confined between the two charged hydrophilic surfaces, have been calculated via a series of molecular dynamic calculations in several films with different water contents. A charged semiflexible amphiphilic model and the TIP5P model of water are used in our simulations [Z. Gamba, J. Chem. Phys. 129, 164901 (2008)]. We calculate the diffusion coefficients, reorientational dynamics, and the atomic density profile of water molecules as a function of the number of water molecules per amphiphilic (n(w)). We also analyze the reorientational motion of the amphiphilics and determine a strong correlation between the dynamics of water molecules and the translational and reorientational dynamics of the amphiphilics, as well as a correlation between the reorientational dynamics of the amphiphilics belonging to the upper and lower halves of the studied thin films.