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Citation link: http://nbn-resolving.de/urn:nbn:de:gbv:46-00102778-10
00102778-1.pdf
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Improvements to the Density-Functional Tight-Binding method: new, efficient parametrization schemes and prospects of a more precise self-consistency


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Other Titles: Verbesserungen der Density-Functional Tight-Binding Methode: neue, effiziente Schemata der Parametrisierung und Ausblick auf eine präzisere Selbstkonsistenz
Authors: Bodrog, Zoltán 
Supervisor: Bálint, Aradi 
1. Expert: Frauenheim, Thomas
2. Expert: Gotthard, Seifert 
Abstract: 
After an introduction to the Density-Functional Tight-Binding (DFTB, a pairwise, LCAO-based approximation to Kohn Sham DFT) method, I deal with improving the treatment of the so-called repulsive energy. This pairwise, quasi-classical interaction energy of atoms covers the difference between calculated Kohn Sham energy and total DFTB energy. Parametrization of DFTB means the time-consuming task of optimizing repulsive potentials for every atomic type pair. To ease this task, I present an automaton that optimizes for different energetical targets, with a few example applications. I also propose the first steps of calculating repulsive potentials, instead of fitting them, and give the first preliminary results of this approach. Last, I propose several pieces of enhancement to the Self-Consistent-Charges (SCC) regime, the second-order extension of DFTB based on effective interactions between point-like atomic charge fluctuations. First, I derive a multipole extension of SCC, and second, I propose some semiempirical improvements to effective interaction profiles between atomic Mulliken charges.
Keywords: DFT, tight binding, DFTB, SCC-DFTB, LCAO, parametrization, second order
Issue Date: 23-Mar-2012
Type: Dissertation
URN: urn:nbn:de:gbv:46-00102778-10
Institution: Universität Bremen 
Faculty: FB1 Physik/Elektrotechnik 
Appears in Collections:Dissertationen

  

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