Modelo molecular para o magnetismo em ferro, cobalto e nÃquel

AUTOR(ES)

Josà Ribamar da Silva Santos

DATA DE PUBLICAÇÃO

2009

RESUMO

We have proposed a molecular model to magnetism in Fe, Co e Ni. To we carried through molecular orbital ab initio calculations using the density functionals UB3LYP, UBLYP, UBHLYP, UBP86, UBP386, UB3PW91, PBE1PBE e LSDA. We, also use the methods UHF, CIS and MP4. The basis used were 6-311G(d,p), LanL2DZ e LanL1mb. The computacional calculations mention the states to it triplet, quintet and septet of the Fe2, Co2 e Ni2 clusters. We did not consider we self to study the isolated molecule Fe2, Co2 e Ni2, and yes a model for our crystal. We analyze for each in the distance interatomic system, the total energy, the width of bands, exchange splittings magnetic and energies HOMO in the level of Fermi (EF). We point out the fact of that Stoner stops, the ferromagnetism is conditional to the presence of strong antibonds states in the level Fermi ( EF) and this was evidenced in our research. Finally, we verify that the molecular model pointed out we show a good understanding of the 3d magnetism. This work is organized in four chapters. In the chapter, we consider the historic and the fundamentals of the magnetism. In the second chapter, we describe the theoretical procedure that we utilized in this work. In the third chapter, we presented our results and discussions. Lastly in the last chapter, we pointed out ours conclusions that are quite relevants in respect to this study, our perspectives, and the references.

ASSUNTO(S)

molecular orbital calculation quimica quantum chemistry magnetism quÃmica quÃntica magnetismo cÃlculo de orbitais moleculares

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