Seite - 84 - in Charge Transport in DNA - Insights from Simulations

ChargeTransport inMicrohydratedDNA Figure6.3: Maximumof transmission functioncalculatedwith theLandauer–Büttiker method for all of the DNA oligos in the different microhydrated environ- ments. (Medianvalues obtained along15nsMDsimulations.) 6.3 ChargeTransportCalculations The model Hamiltonian containing the obtained CT parameters can be used as a basis for the approximative calculation of the electronic transmission function supportedby the systemwithin theLandauer–Büttiker framework.[127] Here again, the previously developedmulti-scale framework,[45] already success- fully applied to fullyhydratedDNAspecies,[44]wasused. The transmission functionwasevaluated for7,500 snapshots alongeveryMDsim- ulationof15ns. Themaximumvalueof the functionwas recorded for every snap- shot, andthemedianvaluewas takentorepresenteachdistributionsofmax. trans- missionobtained in thatway. Fig.6.3 shows thesemedianvaluesobtained foreach of the DNA sequences, in full aqueous solution as well as in the microhydrated systemsDry1 toDry4. The transmission increases in theDry1 systemincomparison to the fullyhydrated one for five out of sevenDNAoligos. This effect is less obvious for the systems Dry2, possibly due to the slightly distorted helical structure at this level of hy- dration. With further reducedwater content inDry3 andDry4, DNAsuffers from severedistortionsandthetransmissionvanishes infiveof thestudiedDNAspecies. 84