Optical spectra from molecules to crystals: Insight from many-body perturbation theory

Quasiparticle spectra, absorption spectra, and excitonic properties of NaI and SrI2 from many-body perturbation theory

We investigate the basic quantum-mechanical processes behind the nonproportional response of scintillators to incident radiation responsible for reduced resolution. For this purpose, we conduct a comparative first-principles study of quasiparticle spectra on the basis of the G0W0 approximation as well as absorption spectra and excitonic properties by solving the Bethe-Salpeter equation for two ...

Excitons in molecular crystals from first-principles many-body perturbation theory: Picene versus pentacene

Pierluigi Cudazzo,1 Matteo Gatti,1 and Angel Rubio1,2 1Nano-Bio Spectroscopy Group and ETSF Scientific Development Centre, Departamento Fı́sica de Materiales, Universidad del Paı́s Vasco UPV/EHU, Centro de Fı́sica de Materiales CSIC-UPV/EHU-MPC and DIPC, Avenida Tolosa 72, E-20018 San Sebastián, Spain 2Fritz-Haber-Institut der Max-Planck-Gesellschaft, Theory Department, Faradayweg 4-6, D-14195 Ber...

Many - body theory of gamma spectra from positron - atom annihilation

A many-body theory approach to the calculation of gamma spectra of positron annihilation on many-electron atoms is developed. We evaluate the first-order correlation correction to the annihilation vertex and perform numerical calculations for the noble gas atoms. Extrapolation with respect to the maximal orbital momentum of the intermediate electron and positron states is used to achieve conver...

Optical Elastography: From Theory to Clinical Applications

Quantum Many–Body Problems and Perturbation Theory

We show that the existence of algebraic forms of exactly-solvable A−B− C−D and G2, F4 Olshanetsky-Perelomov Hamiltonians allow to develop the algebraic perturbation theory, where corrections are computed by pure algebraic means. A classification of perturbations leading to such a perturbation theory based on representation theory of Lie algebras is given. In particular, this scheme admits an ex...