Ferromagnetic Bonf of Li10 Cluster: an Alternative Approach in Terms of Effective Ferromagnetic Sites

C. Cárdenas
Departamento de Física, Facultad de Ciencias, Universidad de Chile, Santiago, Chili & Centro para el Desarrollo de la Nanociencia y la Nanotecnología (CEDENNA), Santiago, Chili
Mercredi 5 Juillet 2017, 14h00
bibliothèque LCT, tour 12 - 13, 4ème étage

In this talk, a model to explain the unusual stability of atomic lithium clusters in their highest spin multiplicity is presented and used to describe the ferro magnetic bonding of high-spin Li10 and Li8 clusters. The model associates the (lack of-) fitness of Heisenberg Hamiltonian with the degree of (de-) localization of the valence electrons in the cluster. It is shown that a regular Heisenberg Hamiltonian with four coupling constants cannot fully explain the energy of the different spin states. However, a more simple model in which electrons are located not at the position of the nuclei but at the position of the attractors of the Electron Localization Function (see Figure) succeeds in explaining the energy spectrum and, at the same time, explains the ferromagnetic bond found by Shaik using arguments of valence bond theory. In this way, two different points of view, one more often used in physics, the Heisenberg model, and the other in chemistry, valence bond, come to the same answer to explain those atypical bonds.

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Acknowledgments
This work was financed by FONDECYT through projects No 1140313 and 1130202, and also by Centers Of Excellence With Basal/Conicyt Financing, Grant FB0807, CEDENNA.