Past projects

Photoionization of nucleic acid components

The effect of high-energy radiation on nucleic acids has received much attention during several past decades.  DNA can be ionized by several mechanisms and furthermore, resulting positive charge migrates. For understanding the charge transfer along the helix of DNA, it is necessary to know ionization potential of each component of the system in realistic environment, i.e. in solution.

DNA_mechanisms

The ionization process in nucleic acid components in the gas phase and in the solution is investigated by means of computational chemistry and compared with available experimental data. One of the general conclusions is that the solvent is very efficient in screening the interactions. From the perspective of radiation-biomolecule interaction, the biomolecule can thus be seen as composed of independent moieties.

Modeling of solvation

Solvation can be modelled using several alternative approaches :  microsolvation of the solute, continuum solvent model and hybrid models.

solvation 

Multivalent phospate anions serve as a test of applicability of these models.

Homogeneous ice nucleation in neat and polluted water

Water in nature mostly freezes heterogeneously; in the atmosphere on dust particles and on the ground in contact with inorganic minerals or even on living organism, particularly bacteria which are efficient ice nuclei, now employed also for commercial purposes.  Although most of the ice in the world is formed by heterogeneous processes, homogeneous ice nucleation has also received a lot of attention, since it controls formation of tropospheric cirrus, polar stratospheric clouds, and thunder clouds. It is still not clear, whether homogeneous freezing of small droplets is a volume or surface controlled process. Therefore, in our group we decided to study this process with molecular resolution by means of classical molecular dynamics with empirical potentials.

monitoring of ice nucleation

Computational results showed that freezing preferentially starts in the subsurface of neat water and water covered by pentanoic acid, where this preference is slightly decreased. Nucleation time in these systems is about comparable. Pentanol surface pollution increases the nucleation time by 50% and washes out the subsurface preference.

Microsolvation of ions

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