Signatures of correlation: from excitons to satellites

TitleSignatures of correlation: from excitons to satellites
Publication Typeexternal talk
Sottile, F
Year of Publication2016
Place PublishedWorkshop on Next Generation Quantum Materials, Sao Paulo (Brasil)

One of the simplest, yet most striking, outcomes of electron correlation is the exciton. The creation of electron-hole pair(s), under external perturbation, is an intrinsic collective excitation of the system and, from the theoretical point of view, is defined
in terms of 'beyond single-particle'.
In this contribution I will first illustrate the importance of excitonic effects in the optical
spectrum of solids, taking Vanadium dioxide as an example, underlying some general (local fields, de-polarization effects) and technical
aspects (starting point of perturbative approaches, self-consistency). In a second part, I will focus on the generality of the screening concepts, and the interchange among theoretical approaches: Bethe-Salpeter equation, Time Dependent Density Functional Theory,
GW approximation) as well as spectroscopy techniques (optical, Inelastic X-ray scattering, Electron Energy Loss and Photo-emission spectroscopy).

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