Spin-orbit interaction location

The Fermi surface of WC was proposed based on magnetoresistance and de Haas-van Alphen data taken under high magnetic fields at low temperatures. WC is a semimetal with equal numbers of electron and hole carriers of 1.5 X 1021/cm3. The Fermi surfaces consist of two electron pockets located at the point A and four hole pockets located at the point L, and at the point K or along the T A axis. These results indicate that the spin-orbit interaction is very important in WC. 

In describing the magneto-optical properties one has to take account of the spin-orbit splitting, which was not included in the band-structure calculations of de Groot et al. These authors note that no orbital quenching occurs at the F point in the Brillouin zone so that here one may expect the spin-orbit interaction to be a maximum. It follows from the magneto-optical spectra that the onset of the Kerr peak at about 2 eV is located near 1 eV (see fig. 37). From these considerations it follows that the transition responsible for the large Kerr intensity involves initial electron states located rather close to the top of the valence band (at F in the lower... 

It might be anticipated that, just as the correlation between the spatial motions of electrons was recognized in the pair function, there ou t to be a 2-electron function that would recognize the correlation between spins of electrons located in different volume elements. Such functions have indeed been defined and used in discussion of spin-coupling effects that arise when relativistic terms are included in the Hamiltonian (McWeeny, 1965). Here we need only note that two functions are required, a spin-orbit coupling function Q, which fully determines spin-orbit interactions, and a spin-spin coupling function which... 

The most common and also most effective mechanism of radical stabilization involves the resonant delocalization of the unpaired spin into an adjacent 7r system, the allyl radical being the prototype case. A minimal orbital interaction diagram describing this type of stabilization mechanism involves the unpaired electron located in a 7r-type orbital at the formal radical center and the 7r- and tt -orbitals of the n system (Scheme 1). 

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