Dresden 2009 – scientific programme

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SYAI: Symposium Ab-Initio Approaches to Excitations in Condensed Matter

SYAI 1: Invited Talks

SYAI 1.5: Invited Talk

Thursday, March 26, 2009, 17:30–18:00, SCH 251

Local excitations in strongly interacting charge-transfer insulators: Frenkel excitons within TD-LDA+U and strong coupling theory — •Wei Ku — Brookhaven National Lab, Upton, NY 11973, USA — Physics Department, Stony Brook University, Stony Brook, NY 11794, USA

Recent theoretical developments to better understand strongly bound local Frenkel excitations in “charge-transfer insulators” will be presented. First, the use of symmetry-respecting first-principles Wannier functions will be demonstrated to unify the description of charge-transfer insulators with the Mott insulators. Second, formal theoretical framework of TD-DFT with LDA+U will be developed and applied to a case study illustrating its capability and deficiency. Third, systematic framework of strong coupling approach will be presented to account for the multiplets beyond the typical solutions of Bethe-Salpeter equation. Finally, a two-particle hopping kernel is introduced to describe propagation of the local excitations. Case studies include anisotropy of local excitations in NiO[1] and space-time propagation of excitons in LiF[2].

[1] B. Larson et al, Phys. Rev. Lett. 99, 026401 (2007).

[2] P. Abbamonte et al, Proc. Natl. Acad. Sci. 105, 12159 (2008).