Métodos Monte Carlo Quântico e Outer Valence Green s function aplicados na obtenção de energias de ionização de sistemas atômicos e moleculares e na construção e interpretação de diagramas de correlação / Quantum Monte Carlo and Outer Valence Green s function methods applied to obtain ionization energies of atomic and molecular systems and to construction and interpretation of correlation diagrams

AUTOR(ES)
FONTE

IBICT - Instituto Brasileiro de Informação em Ciência e Tecnologia

DATA DE PUBLICAÇÃO

25/03/2011

RESUMO

The study was divided into 4 parts: Simple Ionization Energies: We evaluated the ability of MQC and OVGF methods in describing the values of the ionization energy of valence and core and tested the use of relaxed wave functions. The range of deviations obtained with the method of diffusion quantum Monte Carlo (MCQD), in relation to the experimental values, is comparable to other methods such as DFT (Density Functional Theory) and CCGF (Coupled-Cluster Green s Function), from 0.01 to 2 eV, and it was found that the use of the relaxed wave functions is important in the description of core ionizations. Successive Ionization Energies: We estimated the successive ionization energies of successive elements of the 2nd period from the orbital energies of the neutral system and compared with results obtained using the methods MCQ with the wave function of nonionized system. It can be shown the failure of the orbital energies to describe the successive ionization energies and to obtain corrections with the use of MCQ methods. Correlation Diagrams: Diagrams of total electronic energy and quantitative correlation diagrams were constructed using the ionization energy as binding energy for molecules of the type BAB (Li2O and H2O) through the use of MCQ methods. We constructed Bader¿s partial charges diagrams with the discrete charge distributions obtained with MCQ methods to try to interpret the correlation diagrams, but the interpretation by direct comparison was not possible, however, important information was obtained through diagrams of partial charges. Double Ionization Energies: We calculated double ionization energies of atomic and molecular systems by the OVGF method and compared the results obtained with the Density Functional Theory (DFT). The OVGF method proved to be as accurate as the DFT theory in describing the double ionization energies.

ASSUNTO(S)

monte carlo quantico outer valence green s function energias de ionização diagramas de correlação quantum monte carlo outer valence green s function ionization energies correlation diagrams

ACESSO AO ARTIGO

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