A molecular dynamics study of the stability of small prenucleation water clusters

<p>"The dynamical stability and internal energy distribution of prenucleation water embryos have been studied by the molecular dynamic's method. Water clusters containing either five or twenty molecules were chosen to represent prenucleation embryos of small or intermediate size. A central force potential model of water which allows energy to be absorbed into intramolecular modes so that bond lengths and bond angles could adjust to changes in molecular environments was employed to describe the interaction between all pairs of atoms. The motion of the molecules was followed for extended time periods (of the order of several picoseconds) at each of a number of internal energies. Studies on the pentamers showed that below 90 ° K all isomeric, locally stable structures can persist for the entire duration of simulation without significant structural changes. Between 90 to 230 ° K structural interconversion took place. Above 230 ° K all isomeric structures converted to a cyclic ring structure. As energy was further increased, this structure also became unstable. Structure permutations with bona breaking and reforming occurred more and more frequently as energy was gradually added to the cluster. Finally at around 300 ° K a molecule was evaporated from the cluster. Studies on the twenty-molecule cluster showed that structure disruption occurred when there was a large disturbance in the liberational energy of the molecule. The clathrate structure was found to be stable at temperatures of the order of 67 ° K. The statistical mechanical and kinetic implications of these results are discussed.</p> <p>Preliminary work was also done to model the growth mechanism in nucleation by simulating the collision of a monomer with the cluster and following the subsequent absorption and/or scattering phenomenon. These simulations provided information about energy transfer mechanisms and the role of the internal degrees of freedom in absorption processes. Simulations of this type could also help to model and explain the more complex surface absorption process"-- Abstract, pp. ii-iii</p>

Name thesis:degree_name

Ph. D. in Physics

Grantor

University of Missouri--Rolla

Year dc:date.available

2016

Author dc:creator

• Chen, Tze-Shan

• Physics

Repository record dc:identifier

https://scholarsmine.mst.edu/doctoral_dissertations/107

OAI identifier oai:identifier

oai:scholarsmine.mst.edu:doctoral_dissertations-1109