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PGI-1 Seminar: Dr. Matteo Cococcioni

Ab initio modeling of transition metal compounds with Hubbard-corrected DFT functionals

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25 Nov 2014 14:00
venue
PGI Lecture Hall

EPF Lausanne, Switzerland

Abstract:

Transition metal compounds are materials of unquestionable versatility and an accurate modeling of their electronic, magnetic and structural properties is essential for a deeper understanding of their behavior and for the development of innovative applications. However, the importance of electronic correlations makes first-principles calculations on these systems very challenging.

Hubbard-rooted corrections to approximate DFT functionals (DFT+U) have proved able to improve significantly the description of correlated materials and have asserted themselves as the standard choice to approach the study of these systems when high efficiency is required. In this talk I will show how the first principles evaluation of the electronic interactions and some recently completed extensions to their formulation have significantly improved the accuracy, the predictive power and the versatility of the corrective functionals. These methodological advancements will be discussed both on a theoretical level and through their application on paradigmatic systems and the comparison of their results with those obtained from approximate DFT and standard Hubbard corrections.

In the first part, I will illustrate how the inclusion of inter-atomic interactions in the corrective Hubbard Hamiltonian improves the calculation of the energetics and structural properties of both band and Mott insulators and, in particular, of mixed-valence oxides used as Li-ion batteries cathodes. Intra-atomic (Hund’s rule) magnetic couplings will be discussed, instead, in the second section, where their explicit inclusion in the corrective functional will be used to capture the ground state of systems (as CuO) characterized by an intimate correlation between electronic localization and magnetism. The third part of my presentation will focus on the calculation of the phonon spectrum of materials from their correlated ground state through the use of Hubbard-corrected Density Functional Perturbation Theory on MnO and NiO. The forth example will illustrate the application of DFT+U to the study of inter-metallic Heusler alloys and will highlight the importance of correlation effects on the modeling of the magneto-structural transitions these materials undergo. Finally, I will discuss further theoretical extensions to be developed in the near future.




Contact

Prof. Dr. Stefan Blügel
Phone: +49 2461 61-4249
Fax: +49 2461 61-2850
email: s.bluegel@fz-juelich.de

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