Main field of study: Physics
Name of qualification: Master
Area of specialization: Molecular Biophysics and physics of polymers
Supervisor: A. I. Kononov
Reviewer: prof. P. N. Vorontsov-Velyaminov

Influence of stacking geometry on the excitation spectra of nucleobase dimers
D. A. Maksimov
In our study for the first time we addressed the question about the relationship between conformation of the stacked bases and their excitation spectra in attempt to determine the structures most sensitive to solar radiation. The excitation spectra were calculated using CIS(D), CC2, and ADC(2) approaches and aug-cc-pVDZ basis set. It appeared that all the studied dimers that fall in the conformational range of d≲3.3 Å (distance between the midpoints of the C6-C5 bonds) and η≲50° (dihedral angle C5-C6-C6-C5) exhibited ππ* excitonic transitions red-shifted by ≥0.4 eV from the absorption maximum of canonical B-form dimers. Most of these conformations were found in curved, hairpin-like DNA and RNA motifs, and highly distorted B-form DNA structures. We thus conclude that the hotspots of CPD formation and other photoproducts under solar radiation are most likely placed in such sites with non-canonical stacked geometries.