Incollection,
Democratic particle motion for meta-basin transitions in supercooled water
Abstract Book of the XXIII IUPAP International Conference on Statistical Physics, Genova, Italy, (9-13 July 2007)
Abstract
We use molecular dynamics computer simulations to investigate the
local motion of particles in a supercooled complex liquid and how
this relates with the Potental Energy Landscape (PEL) exploration.
A new powerful method to investigate the mechanisms
controlling the PEL exploration is introduced.
This new method, the Distance Matrix methods, has recently been
successfully applied to the study of a
simple liquids Appignanesi et al.,Phys. Rev. Lett. 96, 057801
(2006), allowing a clear definition of the metabasin concept
and supporting the scenario of a random walk on metabasins for the long
time diffusion.
In this talk we apply this method in
a study of supercooled water. We give
a further confirmation that the motion of the system consists in the
metabasin exploration, followed by a sharp crossing to a different
metabasin. Furthermore, we focused on the crossing between metabasins. The new
method allows us to easily identify
the particles participating to the crossing. This particles result to
form relatively compact clusters that act as cooperative relaxing
units. This units could be candidates for the cooperatively
rearranging regions proposed by Adam and Gibbs.
Moreover, we focus on the hydrogen bond role in water diffusion, and
identify the connection between particles participating to the relaxing units
and their role in the tetrahedral hydrogen bond network.
