PhD Thesis: Molecular structure and dynamics of liquid water
Friday 23 October 2015
to 12:15 at
Daniel Schlesinger (Stockholm University, Department of Physics)
Water is abundant on earth and in the atmosphere and the most crucial liquid for life as we know it. It has been subject
to rather intense research since more than a century and still holds secrets about its molecular structure and dynamics,
particularly in the supercooled state, i. e. the metastable liquid below its melting point.
This thesis is concerned with different aspects of water and is written from a theoretical perspective. Simulation
techniques are used to study structures and processes on the molecular level and to interpret experimental results. The
evaporation kinetics of tiny water droplets is investigated in simulations with focus on the cooling process associated
with evaporation. The temperature evolution of nanometer-sized droplets evaporating in vacuum is well described by the
Knudsen theory of evaporation. The principle of evaporative cooling is used in experiments to rapidly cool water droplets
to extremely low temperatures where water transforms into a highly structured low-density liquid in a continuous and
For water at ambient conditions, a structural standard is established in form of a high precision radial distribution
function as a result of x-ray diffraction experiments and simulations. Recent data even reveal intermediate range molecular
correlations to distances of up to 17 Å in the bulk liquid.
The barium fluoride (111) crystal surface has been suggested to be a template for ice formation because its surface lattice
parameter almost coincides with that of the basal plane of hexagonal ice. Instead, water at the interface shows structural
signatures of a high-density liquid at ambient and even at supercooled conditions.
Inelastic neutron scattering experiments have shown a feature in the vibrational spectra of supercooled confined and
protein hydration water which is connected to the so-called Boson peak of amorphous materials. We find a similar feature
in simulations of bulk supercooled water and its emergence is associated with the transformation into a low-density liquid