Stuttgart 2012 – wissenschaftliches Programm

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MO: Fachverband Molekülphysik

MO 13: Poster 1: Cold Molecules, Femtosecond Spectroscopy, Molecular Dynamics

MO 13.30: Poster

Dienstag, 13. März 2012, 16:30–19:00, Poster.IV

Non-adiabatic on-the-fly molecular dynamics on the formation of the DNA Dewar photolesion: Implementation of ONIOM and CASPT2 — •Sven Oesterling, Artur Nenov, Benjamin P. Fingerhut, and Regina de Vivie-Riedle — Ludwig Maximilians Universität München, Department Chemie

Semiclassical on-the-fly dynamics provide a way to simulate molecular processes of moderate sized systems. Treating the nuclei classically, abolishes the need to precompute potential energy surfaces, and thus allows for a full dimensional treatment of the molecular degrees of freedom. The electronic properties are computed with quantum chemical methods, adequate for system-size and nature of the problem. This combination makes the whole approach an useful tool to investigate non-adiabatic reactions in many biologically relevant molecules, such as the nucleobases.

In the process of describing the formation and reversion of the DNA Dewar photolesion, we implemented an interface for the Molpro quantum chemistry package, in the Newton-X dynamics package. The two main features are the complete active space perturbation theory (CASPT2) and a hierarchical layer scheme (ONIOM). While CASPT2 yields very precise results for the electronically excited bases, the ONIOM method enables embedding the photoactive fragments into the phosphate-desoxyribose backbone, treated with computationally less demanding ground-state methods. In this way both, photochemical, as well as sterical effects can be accounted for, in an appropriate fashion.