Molekulové simulace nukleace ledu

Pluhařová, Eva

Title: Molecular simulations of ice nucleation Author: Eva Pluhařová Department: Department of Physical and Macromolecular Chemistry Faculty of Science UK Advisor: doc. Mgr. Pavel Jungwirth, DSc., IOCB AS CR, v.v.i. Advisor's e-mail address: pavel.jungwirth@uochb.cas.cz Abstract: By means of molecular dynamics simulations we have systematically investigated homogeneous ice nucleation in neat and surface contaminated water. As models of the adsorbates we have assumed pentanol and pentanoic acid. In neat water nucleation preferentially starts in the subsurface region, which accommodates better than the bulk the volume increase associated with freezing. Homogeneous ice nucleation is affected more by alcohol than by acid. Water slabs covered by a disordered layer of pentanol exhibit negligible preference for subsurface nucleation and longer nucleation times in comparison with neat water, while nucleation times are almost unaffected by the presence of pentanoic acid and the subsurface preference is only slightly decreased. We tried to rationalize the differences between the effects of different compounds by their ability to orient water molecules and to change their mobility. The fact that adsorbates differ in the influence on homogeneous ice nucleation has important implications for the microphysics of...

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