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TheoreticalBackground
Figure2.2: Overview of the steps in the multi-scale approach. The MM simula-
tion generates the structure of the molecule. This is passed to the QM
calculation, performed with DFTB2, which generates the Hamiltonian.
This Hamiltonian can be used for charge transport calculations with the
Landauer–Büttiker theory. Or, thewave-function is propagated by the the
mean-field (Ehrenfest) or the surface hoppingmethod. Finally, the atomic
charges in theMMsystemareupdated according to thewave-function.
the calculations. This interaction is crucial for the description of charge transfer
in biomolecular systems and cannot be neglected. The next step in this approach
is to reduce the necessary amount of computation time for the still largeQM re-
gion. Charge transfer is supposed to occur only via the frontier orbitals of the in-
volvedmolecules. In thecaseofholemigration inDNA,only thehighest-occupied
molecular-orbitals (HOMO) of the purine bases are treated explicitly. This can
be seen as a fragment-orbital approach where a part of the electronic structure
is frozen and treated implicitly like the σ and π separation in theHückel theory
[74,75].
2.4.2 TheFragmentOrbitalApproach
To achieve a reasonable computational efficiency, aQM/MMmodel is introduced
where only the excess charge is calculatedwithQMmethodswhile the rest of the
molecule is treatedwith classicalMMmethods. Thegeneral idea is todecompose
the system into M spatially non-overlapping fragments. With this assumption, it
ispossible toperformseparateQMcalculationsof every fragment. Thisprocedure
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Charge Transport in DNA
Insights from Simulations
- Title
- Charge Transport in DNA
- Subtitle
- Insights from Simulations
- Author
- Mario Wolter
- Publisher
- KIT Scientific Publishing
- Date
- 2013
- Language
- English
- License
- CC BY-SA 3.0
- ISBN
- 978-3-7315-0082-7
- Size
- 17.0 x 24.0 cm
- Pages
- 156
- Keywords
- Charge Transport, Charge Transfer, DNA, Molecular Dynamics, Quantum Mechanics
- Categories
- Naturwissenschaften Chemie
Table of contents
- Zusammenfassung 1
- Summary 3
- 1 Introduction 5
- 2 TheoreticalBackground 11
- 3 SimulationSetup 39
- 4 DNAUnderExperimentalConditions 49
- 5 ChargeTransport inStretchedDNA 69
- 6 ChargeTransport inMicrohydratedDNA 79
- 7 AParametrizedModel toSimulateCT inDNA 89
- 8 Conclusion 105
- Appendix 111
- A DNAUnderExperimentalConditions 111
- B CTinMicrohydratedDNA 117
- List ofPublications 137