Fast rotational motion of water molecules increases ordering of hydrophobes in solutions and may cause hydrophobic chains to collapse

作者：Mohoric Tomaz^*; Bren Urban; Vlachy Vojko

来源：Journal of Chemical Physics, 2015, 143(24): 244510.

DOI：10.1063/1.4939085

Using the molecular dynamics simulations with separate thermostats for translational and rotational degrees of freedom, we investigate the effects of water's rotational motion on the interaction among Lennard-Jones solutes. The situation with rotational temperature higher than the translational one (T-R > T-T) is mimicking the effects of microwaves on model solutions. Molecular dynamics simulations suggest that solutions of Lennard-Jones solutes become increasingly more structured with the rise in T-R, while keeping the T-T constant. This is evidenced by an increase of the first and the second peak of the solute-solute radial distribution function. In addition, the first peak moves toward slightly larger distances; the effect seems to be caused by the destabilization of water molecules in the first hydration shell around hydrophobic solutes. More evidence of strong effects of the rotationally excited water is provided by the simulations of short hydrophobic polymers, which upon an increase in T-R assume more compact conformations. In these simulations, we see the re-distribution of water molecules, which escape from hydrophobic "pockets" to better solvate the solvent exposed monomers.

• 出版日期2015-12-28