Estudo teórico de espectroscopia das moléculas diatômicas, AlC e GaC, e estudo de propriedades físico-químicas de microclusters de AlnC, AlnSi e GanC,(n=1-7)

• Autor(a) principal: Fernandes, Gabriel Freire Sanzovo [UNESP]
• Data de Publicação: 2016
• Tipo de documento: Trabalho de conclusão de curso
• Idioma: por
• Título da fonte: Repositório Institucional da UNESP
• Texto Completo: http://hdl.handle.net/11449/155339; http://www.athena.biblioteca.unesp.br/exlibris/bd/capelo/2017-04-17/000881953.pdf
• topic: Espectroscopia molecular; Moleculas; Semicondutores dopados; Quimica quantica; Doped semiconductors

This work involves using methods of molecular quantum chemistry to characterize small molecule agglomerates formed by aluminum atoms and gallium-doped with a carbon atom or a silicon atom, AlnC, and GanC and AlnSi (n = 1-7), in which the purpose is to verify whether the Hume-Rothery rules could be valid for these systems. For the simplest system, AlC and GaC, the methods of multiconfiguration self-consistent field were used in a complete active space (CASSCF) and multireference configuration interaction (MRCI) to characterize both the ground state, as several excited states, including those still previously uncharacterized in the literature. These methods include both static correlation and dynamic correlation and are the most suitable methods for the characterization of excited states and thus for the determination of the electronic spectra and radiative transition probabilities of these states. The AlnC agglomerates, and GanC and AlnSi (n = 1-7) were characterized using a Hm-GGA approximation of the density functional theory (M06) with the basis set of functions 6-311 ++ G (3df, 3pd), in which the search for the global minimum energy conformations was performed by geometry optimizations from various initial geometries, taking into account possible different spatial symmetries, as well as different spin multiplicities. It was found that the lowest energy conformers have high symmetry in the case of smaller agglomerates (AlnC, GanC and AlnSi (n <5)), whereas the larger agglomerates have low spatial symmetry due to a rearrangement of aluminum atoms, or gallium around the carbon atom, which has all unsaturated bonds. Regarding the excited states of the agglomerates, it was found that doped systems have oscillations due the parity of the number of matrix atoms, with much larger excitation energy in the pure agglomerates of aluminum and gallium, particularly for systems with few atoms... (Completo abstract click electronic access below)