Two or More Magnetic Centers

1 Localized Versus Delocalized Description of the Two-Electron/Two-Orbital Problem 

Configuration Interaction using delocalized orbitals We first consider the case where the two magnetic electrons are coupled to a spin triplet, 5=1. The simplest description of the Ms = 1 component of the lowest lying triplet state is one single Slater determinant 

Graaf and R. Broer, Magnetic Interactions in Molecules and Solids, 

The orbitals i and (p2 are occupied with one electron and are often referred to as the magnetic orbitals. The Slater determinant shown in Eq. 3.2a has the correct spin symmetry for the Ms = 1 component of an 5 = 1 manifold, the corresponding wave function of the = -1 component is given by 

These three S = 1 wave functions belong to the electronic configuration. which in addition gives rise to a spin-singlet wave function, 

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The problem of the ferromagnetism of a solid ion-radical salt has two important points. One is ferromagnetism at the level of a salt as the molecule, which consists of two paramagnetic species. Another is ferromagnetism at the level of a solid sample formed from assemblies of the spin-bearing molecules. These molecules may contain one or more magnetic centers. 

If a compound comprises two or more different spin centers with different magnetic moments (e.g., Fe(II), S 2, and Fe(ffl), S = 5/2) that are antiferromagne-tically coupled and if the crystal lattice features a pattern of alternating spins of... 

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