I am a condensed matter physicist with a theoretical background aiming at understanding the properties of various systems, from nanotubes to graphene, superconducting diamond or silicon to DNA nucleobasis, using the methodology of ab initio quantum simulations, namely "in silico" study of real materials based on the basic principles of quantum mechanics. Much emphasis is given to contributing to the development of novel approaches, in particular in the so-called field of many-body perturbation theory, to progress in the computer-aided description of materials, in terms of accuracy, complexity of the systems and of the "physical observables" that can be calculated. Current applications focus mainly on methodology for the study of organic and hybrid photovoltaic systems for "green" energy generation (FIESTA initiative).