2019/03/31 by Takuma Kikutsuji, Kang Kim, Nobuyuki Matubayasi · 1 citation
Physics and Astronomy · #cond-mat.soft #physics.chem-ph
paper · pdf · doi:10.1063/1.5095978
published as J. Chem. Phys. 150, 204502 (2019) · 7 pages, 5 figures, J. Chem. Phys. for "Special Topic on Chemical Physics of Supercooled Water"
arxiv created 2019/04/30 · arxiv updated 2019/05/24
The slow dynamics of glass-forming liquids is generally ascribed to the cage-jump motion. In the cage-jump picture, a molecule remains in a cage formed by neighboring molecules, and after a sufficiently long time, it jumps to escape from the original position by cage-breaking. The clarification of the cage-jump motion is therefore linked to unraveling the fundamental element of the slow dynamics. Here, we develop a cage-jump model for the dynamics of supercooled water. The caged and jumping states of a water molecule are introduced with respect to the hydrogen-bond (H-bond) rearrangement process, and describe the motion in supercooled states. It is then demonstrated from the molecular dynamics simulation of the TIP4P/2005 model that the characteristic length and time scales of cage-jump motions provide a good description of the self-diffusion constant that is determined in turn from the long-time behavior of the mean square displacement. Our cage-jump model thus enables to connect between H-bond dynamics and molecular diffusivity.