First-Principles Study of the Electronic and Magnetic Properties of Defective Carbon Nanostructures

Abstract

Graphenic nanostructures represent an important research subject in the fields of nanoscience and nanotechnology. These materials possess extraordinary properties which are supposed to revolutionise the performance of electronic components in the next generation of electronic devices. Several applications within electronics, materials science, condensed matter physics, etc, have been predicted or are already available. The study of graphene has changed in recent years from a theoretical topic to a field where experimental and theoretical advances go hand in hand. In particular, the theoretical studies shown in this thesis are either linked or directly motivated by new experiments. This thesis focuses on the modeling electronic and magnetic properties of defects in car- bon nanostructures. The SIESTA method, based on density functional theory (DFT), was used as the main tool to compute all chemical and physical properties of the studied systems. Other ab initio method was also used in the simulations, the VASP code, which using a different methodology based on plane waves and projector-augmented wave potentials (PAW), allows us to check the possible limitations of the pseudopotentials and localized basis set used in SIESTA. Remarkably, the agreement between both set of calculations is excellent. Other programs were also utilized to analyze and treat the huge amount of data obtained in the simulations. From simple programs in AWK, PYTHON, FORTRAN, up to sophisticated graphical packages used to create some figures displayed in this thesis.