Molecular structure and dynamics of liquid water: Simulations complementing experiments
2015 (English)Doctoral thesis, comprehensive summary (Other academic)
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 accelerated fashion.
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 upon cooling.
Place, publisher, year, edition, pages
Stockholm: Department of Physics, Stockholm University , 2015. , 79 p.
liquid water, supercooled water, molecular simulation, evaporative cooling
Atom and Molecular Physics and Optics Condensed Matter Physics
Research subject Theoretical Physics
IdentifiersURN: urn:nbn:se:su:diva-120808ISBN: 978-91-7649-264-2OAI: oai:DiVA.org:su-120808DiVA: diva2:854642
2015-10-23, sal FB42, AlbaNova universitetscentrum, Roslagstullsbacken 21, Stockholm, 09:15 (English)
Gallo, Paola, Professor
Pettersson, Lars G. M., Professor
At the time of the doctoral defense, the following papers were unpublished and had a status as follows: Paper 1: Manuscript. Paper 4: Manuscript.2015-10-012015-09-172015-10-27Bibliographically approved
List of papers