Aproximação GW: fundamentos e aplicações a novas nanoestruturas bidimensionais

Abstract

The structural and electronic charactezation of bidimensional nano-compounds(2D) is a subject that has been largely studied in materials science. In the present work, we investigate this topic, seeking to go beyond the Density Functional Theory (DFT), the most used method in such studies. Our main motivations are: first of all, it’s known that the DFT theory underestimate the energy gaps, and does not give a well defined physical interpretation of the Kohn-Sham eigenvalues (except for last occupied); in second, our research group has proposed, working with the experimentalists of our department, new 2D materials, for which it’s necessary an accurate electronic charactezation. Therefore, we propose the study of such systems, bilayers of graphene and boron nitride, functionalized with -OH groups under pressure and rehybridizated in the shape of nano-diamonds, using the GW methodology. This formalism is defined by the iterative treatment based on many-body Green’s functions (G) and the screening dielectric function (W), from which the self-energy is approximated, what allow us to go beyond the most used approximations, such as Hartree and Hartree-Fock. Our results point to important corrections in the electronic structure of the studied materials.