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Institute for Computational Physics
"Like-Charge Attraction in DNA" (file does not exist!), 2013, Institute for Computational Physics, Stuttgart
For this thesis, the MMM1D algorithm was ported to GPGPU. This resulted in a 40-fold performance increase over the previous implementation in ESPResSo and now allows for Molecular Dynamics simulations with electrostatic interactions in 1D-periodic geometries with several thousand particles.
Using this, simulations with various simple DNA models were performed. These simulations show that charge discretization and phase shifts between DNA molecules, modeled as rods, have a significant influence on their attractive properties, an effect that previous works disregarded as it was computationally too expensive, even though it turns out to be too large to neglect for realistic results. Curling up the discretely charged rods into helices, thus making the most accurate model of DNA that could be simulated with the limits of time and resources for this thesis, reveals further geometry dependencies and again a strong influence of a phase shift between the two helices. For phase shifts of 180°, the results for the continuous rods are mostly recovered for large Bjerrum lengths, but for any other phase shift, the forces are weaker, albeit still attractive.