Seite - 3 - in Charge Transport in DNA - Insights from Simulations

Summary In thiswork, the charge transport andcharge transfer (CT) capabilities ofdeoxyri- bonucleic acid (DNA) are investigated. Special attention is drawn to the DNA structure and the CT under conditions resembling the experimental setup. The experimental investigations are conductedunder conditionsnot representedaccu- rately inmost theoretical approachesuntil now. A common feature of charge transport experiments is to attach the DNA strand to electrodeswith varying distances. Moreover, single-molecule experiments are conducted in molecular junctions, where the solvent is removed partially with a streamofgas. To explain the outcome of the experiments under such conditions several ques- tions have to be answered. What is the exact amount of water preserved at the DNA strand and howdoes it affect the structure? Howdoes theDNA structure accommodate for externalmechanical stress?What influencehave these structural changeson the charge transport/transfer?Whyhas it an influenceat all? All these questions will be answered in the course of this work. To be able to answer these questions a simulation setup is introduced,which is able todescribe the experimental conditions in combinationwith the calculationofCT inDNA. Although the usedmulti-scale framework for the computation of charge transfer in DNA is one of the fastest available, it still needs large amounts of computa- tional time. To simulate charge transfer processes inDNAsequences of hundreds of nucleobases on time scales larger thannanoseconds, dramatic enhancements in computational efficiency have to bemade. In the final part of thiswork, onepos- sible approach to this is developed - a parametrizedmodel to simulate theCT in DNA.Not onlywill thismodel be able to describe the CT inDNAaccurately, it willmake investigationofvery longDNAsequencesupto thousandsofbase-pairs over extensiveperiodsof timepossible. 3