Berlin 2012 – wissenschaftliches Programm

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DY: Fachverband Dynamik und Statistische Physik

DY 7: Reaction-Diffusion-Systems

DY 7.6: Vortrag

Montag, 26. März 2012, 18:00–18:15, MA 144

Proton-transfer barriers in low-temperature hexagonal ice from computer simulations — •Christof Drechsel-Grau and Dominik Marx — Lehrstuhl für Theoretische Chemie, Ruhr-Universität Bochum, 44780 Bochum, Germany

Hexagonal ice exhibits remarkable properties. For instance, the proton positions remain disordered down to low temperatures (≈ 10 K), thereby giving rise to the residual entropy of ice, which stems from many configurations of the hydrogen-bond network even in the absence of defects. Collective proton-transfer or proton-tunnelling events may connect different (defect-free) proton configurations. Unravelling the proton dynamics would not only shed light on properties of ice, but might also contribute to our understanding of liquid water. In this contribution we investigate whether the barriers between different configurations are sufficiently low for proton dynamics to occur even at low temperature. In particular, we describe the electronic structure via density-functional theory and take into account nuclear quantum effects by means of path-integral simulations. First results indicate that the classical barrier is significantly higher than its quantum counterpart, thereby underlining the importance of nuclear quantum effects.