Fernando Flores - Academia.edu (original) (raw)
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Papers by Fernando Flores
Physical Review B, 2006
In this contribution we address the theoretical understanding of weak chemical interactions and o... more In this contribution we address the theoretical understanding of weak chemical interactions and of the van der Waals forces, in conjunction with the last developments in this area and selected applications to nanostructures. In the first section, we highlight the importance of these interactions, in physics and chemistry and also in biology, and we recall early treatments of these issues, as those by van der Waals and London. After a brief review of the existing methods to treat such interactions, we present a model based on DFT (for each van der Waals-interacting independent system) and an intermolecular perturbation theory that uses a localized orbitals basis set. We will first detail a weak overlap expansion (LCAO-S 2) as a perturbation treatment to determine the weak chemical interaction. Then we will show how to implement the van der Waals interaction in the DFT solution, from the dipolar approximation in a perturbation theory. We apply this model to a reference system for weak interactions, i.e., the interaction between two planes of graphene. In the framework of a minimal basis set that describes each independent system and the weak chemical repulsion, we show that it is necessary to take into account atomic dipole transitions involving high excited states like 3d orbitals to properly describe the van der Waals interaction. We demonstrate how the delicate balance between chemical repulsion and van der Waals attractive interaction gives the equilibrium geometry and the binding energy of the system. Moreover, as an extension of this work, we obtain the adsorption energy of a carbon nanotube on graphene, the adsorption energy of a C 60 molecule on a carbon nanotube, and the energy of a C 60 molecule encapsulated in a carbon nanotube. This gives us the opportunity to discuss
Physical Review B, 2006
In this contribution we address the theoretical understanding of weak chemical interactions and o... more In this contribution we address the theoretical understanding of weak chemical interactions and of the van der Waals forces, in conjunction with the last developments in this area and selected applications to nanostructures. In the first section, we highlight the importance of these interactions, in physics and chemistry and also in biology, and we recall early treatments of these issues, as those by van der Waals and London. After a brief review of the existing methods to treat such interactions, we present a model based on DFT (for each van der Waals-interacting independent system) and an intermolecular perturbation theory that uses a localized orbitals basis set. We will first detail a weak overlap expansion (LCAO-S 2) as a perturbation treatment to determine the weak chemical interaction. Then we will show how to implement the van der Waals interaction in the DFT solution, from the dipolar approximation in a perturbation theory. We apply this model to a reference system for weak interactions, i.e., the interaction between two planes of graphene. In the framework of a minimal basis set that describes each independent system and the weak chemical repulsion, we show that it is necessary to take into account atomic dipole transitions involving high excited states like 3d orbitals to properly describe the van der Waals interaction. We demonstrate how the delicate balance between chemical repulsion and van der Waals attractive interaction gives the equilibrium geometry and the binding energy of the system. Moreover, as an extension of this work, we obtain the adsorption energy of a carbon nanotube on graphene, the adsorption energy of a C 60 molecule on a carbon nanotube, and the energy of a C 60 molecule encapsulated in a carbon nanotube. This gives us the opportunity to discuss