Berlin 2015 – wissenschaftliches Programm

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TT: Fachverband Tiefe Temperaturen

TT 82: Electronic Structure Theory: General, Method Development (organized by O)

TT 82.5: Poster

Mittwoch, 18. März 2015, 18:15–21:00, Poster A

Precise dynamical response functions in all-electron methods: application to the RPA correlation energy — Markus Betzinger, •Christoph Friedrich, and Stefan Blügel — Peter Grünberg Institut and Institute for Advanced Simulation, Forschungszentrum Jülich and JARA, Germany

The main obstacle in calculating dynamical response functions in practice is their slow convergence with respect to the basis-set size and the number of unoccupied bands. We showed in Refs. [1,2] for the static Kohn-Sham (KS) density response in the all-electron FLAPW method that an incomplete-basis-set correction (IBC) gives rise to a much better convergence behavior. The IBC contains a basis response term that provides response contributions that lie outside the Hilbert space spanned by the original basis. These contributions, therefore, incorporate to some extent an infinite number of states. We present an extension of the IBC to the frequency domain and demonstrate that precise RPA response functions can be obtained already with small basis-set sizes and few numbers of unoccupied states. As an example, we apply the correction to the RPA correlation energy of KS density-functional theory, whose central ingredient is the RPA response function.

[1] M. Betzinger et al., Phys. Rev. B 85, 245124 (2012).

[2] M. Betzinger et al., Phys. Rev. B 88, 075130 (2013).