Fast Anomalous Diffusion of Small Hydrophobic Species in Water

Barbara Kirchner, John Stubbs, and Dominik Marx

Phys. Rev. Lett. 89, 215901 – Published 4 November 2002

Abstract

Using Car-Parrinello molecular dynamics a structural diffusion mechanism for the simplest hydrophobic species in water, an H atom, is proposed. The hydrophobic solvation cavity is a highly dynamical aggregate that actually drives, by its own hydrogen-bond fluctuations, the diffusion of the enclosed solute. This makes possible an anomalously fast diffusion that falls only short of that of “Grotthuss structural diffusion” of $H^{+}$ in water. Here, the picture of a static, i.e., “iceberglike,” clathrate cage is a misleading concept. The uncovered scenario is similar to the “dynamical hole mechanism” found in a very different context, that is, large molecules moving in hot polymeric melts.

Received 2 July 2002

DOI:https://doi.org/10.1103/PhysRevLett.89.215901

Authors & Affiliations

Barbara Kirchner^*, John Stubbs^†, and Dominik Marx^‡

Lehrstuhl für Theoretische Chemie, Ruhr-Universität Bochum, 44780 Bochum, Germany

^*Present address: Physikalisch-Chemisches Institut, Universität Zürich, 8057 Zürich, Switzerland.
^†On leave from Department of Chemistry, University of Minnesota, Minneapolis, MN 55455-0431.
^‡Corresponding author.

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Issue

Vol. 89, Iss. 21 — 18 November 2002

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