Semiconductors composed of organic molecules are promising as components for flexible
and inexpensive optoelectronic devices, with many recent studies aimed at understanding …

Using the simple (symmetric) Hubbard dimer, we analyze some important features of the GW
approximation. We show that the problem of the existence of multiple quasiparticle solutions …

We report an exhaustive study of the performance of different variants of Green function
methods for the spherium model in which two electrons are confined to the surface of a …

Similar to other electron correlation methods, many-body perturbation theory methods based
on Green's functions, such as the so-called GW approximation, suffer from the usual slow …

The optical absorption spectra of the azobenzene-functionalized metal–organic framework
(MOF), PCN-123, are calculated in cis and trans configurations using the Bethe–Salpeter …

The use of atomic orbitals in Hedin's GW approximation provides, in principle, an
inexpensive alternative to plane-wave basis sets, especially when modeling large …

In this thesis, an ab initio theoretical framework for the investigation of spin excitations and
the electron-magnon scattering is developed within many-body perturbation theory and …

Climate change is pushing humankind to seek alternative and renewable ways to meet their
growing energy demands. Catalytic reactions, such as water splitting into molecular …

Recent experimental discovery of narrow emission red phosphor Sr [Li2Al2O2N2]: Eu2+
enables a potential noticeable leap in the luminous efficacy of phosphor based white LEDs …

In this thesis, I investigate the excited-state properties of molecules within the Many-Body
Perturbation Theory (MBPT) framework. MBPT is formulated as a hierarchy of coupled …