The structure of a DMSO-water mixture from Car-Parrinello simulations

The mixture of DMSO-water was studied with Car-Parrinello simulation techniques. A threefold coordination at the DMSO oxygen, methyl group hydrogen-oxygen atom contacts, Russel-structures and 1-DMSO-3-H2O clusters are observed. The H(DMSO)-O(H2O) and the H(DMSO)-H(H2O) radial distribution functions are almost identical. For different far water the angular distribution displays a dialectic character: close water orient with the oxygens to the methyl hydrogen far waters vice versa. The emerging picture for the dynamical behavior of the methyl groups is that of a near-hydrophilic-far-hydrophobic, where the hydrophobic character is probably dominant. A detailed mechanism of one such an event is given, (C) 2002 Elsevier Science B.V. All rights reserved.