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Energy Density Functionals From the Strong-Interaction Limit of Density Functional Theory
Mirtschink, A.P.
2015
DOI (link to publisher)
10.6084/m9.figshare.1254927
document version
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Link to publication in VU Research Portal
citation for published version (APA)
Mirtschink, A. P. (2015). Energy Density Functionals From the Strong-Interaction Limit of Density Functional
Theory. https://doi.org/10.6084/m9.figshare.1254927
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Energy Density Functionals From the Strong-Interaction Limit of Density Functional Theory
André Mirtschink, PhD student in the Department of Theoretical Chemistry, investigated density functional approximations for the description of strong electronic correlation. His developments can be used for the realistic modeling of electronics and pave the way for a new generation of approximate functionals in chemistry.
Strong correlation effects as present in metallic- and semiconductor structures at nano-meter scale or whenever a chemical bond is broken are notoriously diffi cult to model by computational implementations of density functional theory (DFT). Although it is known for decades that in principle the exact density functional exists, present day simulation technics exclusively rely on approximations for the reason of computational effi ciency. To motivate accurate approximations formal knowledge on the exact functional can be used. From recent advances the exact functional became available in the strong-interaction limit of DFT and with this new piece of information it is now possible to derive approximate functionals that correctly describe strong-correlation.
Derivation and pilot applications of functionals for strong electronic correlation
In his PhD research, André Mirtschink explored approaches for the construction of functional approximations by inclusion of the strong-interaction limit of DFT. He combined by interpolations the rigorous formulation of the exact functional in the strong-interaction limit with its exact counterpart from the weakly interacting limit. Thereby a balanced description of the electrons as perfectly correlated point charges and as non-interacting quantum mechanical particles is achieved, and, when implemented in a self-consistent manner, the competition of the classical effects with the quantum mechanical effects realistically models strong electronic correlation within DFT.
After motivating his functionals from purely formal arguments, Mirtschink progresses to demonstrate by pilot calculations that his functionals capture strong correlation in models for quantum wires, quantum dots and chemical systems. A first assessment of his functionals for the accurate modeling of compounds in any correlation regime is also undertaken by tuning the correlation strength in the quantum wire and quantum dot models, and by considering the anions of the Helium isoelectronic series. Further, his functionals are shown to exhibit crucial features of the exact functional that are required for the modeling of charge transport through conductors and long-range charge transfer in photo-induced chemical processes.
Mirtschink's developments can be already used to model electronic correlation in strongly correlated quantum wires and quantum dots. For systems in intermediate correlation regimes his functionals serve as a starting point for functional approximations alternative to the traditionally established approximations.
