Química computacional: um estudo multidisciplinar dentro das subáreas da química através do modelo de Hartree-Fock

• Autor(a) principal: Nicholson, Melany Isabel Garcia [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/11449/155539; http://www.athena.biblioteca.unesp.br/exlibris/bd/capelo/2017-06-19/000885547.pdf
• topic: Hartree-Fock, Aproximação de; Cálculo; Atomos; Moleculas; Orbitais atomicos; Molecules

Schrödinger's equation was a great advance in science at the time it was published, making it possible for quantum mechanics to develop and transform itself into a field of knowledge in which many researchers still work today. However, the Schrödinger method has its limitations, the most important one being the fact that is does not exactly resolve problems involving more than one electron. So, right after the publication of Erwin Schrödinger's work, another scientist, called Douglas R. Hartree, started working on a theoretical method in which he and another scientist called Vladimir Fock inserted approximations in a way as to allow the Schrödinger equation to be solved numerically. In the current work, the objective was to deepen and detail the Hartree-Fock method to then apply it to certain cases to see in which systems it would work and in which systems it would not, and then define the reasons for that behavior. In this way, the ionization energy and electron affinity were calculated for lithium, sodium and potassium, applying Koopmans' theorem to both of these situations. Calculations were also made to determine the bond distance for H2, N2 and O2, the ground state and dissociation energies for the H2 molecule and lastly, calculations were made to determine how the electrons distribute themselves in the N2 and O2 molecules, situation in which we tried to predict the fundamental state for these two molecules, with the possibilities being either singlet or triplet. We also studied, in a simplified way, the influence of different base sets for the ionization energy and electron affinity calculations, using the 6-31G and cc-pVTZ base sets. The results showed that the method worked well for the determination of the ionization energies for lithium, sodium and potassium, even though error cancelling occurs while the calculations are in process. In this manner, Koopmans' theorem can