Transition elements spin polarization

The complete experiment for 2p photoionization in magnesium described previously depends on the validity of the non-relativistic LSJ-coupling scheme and on the existence of a simple subsequent Auger transition. However, such conditions are rarely met, since in heavier elements spin-orbit effects cannot be neglected, and for outer-shell photoionization no subsequent decay is possible. In order to perform a complete experiment for such cases,f measurement of the spin-polarization of the photoelectrons is necessary. As an example, 5p photoionization in xenon will be discussed. 

The transition metal atom has a possibility to possess a magnetic moment in metaUic material, then an investigation of the spin polarization of the cluster from a microscopic point of view is very important in understanding the magnetism of the metallic materials. We try to explain the spin polarization and the magnetic interactions of the cluster in terms of the molecular orbital. For the heavy element in the periodic table whose atomic number is beyond 50, it is mentioned that the relativistic effects become very important even in the valence electronic state. We perform the relativistic DV-Dirac-Slater calculation in addition to the nonrelativistic DV-Xa calculation for the small clusters of the 3d, 4d and 5d transition elements to clarify the importance of the relativistic effects on the valence state especially for the 5d elements. 

The electronic state calculations of transition metal clusters have been carried out to study the basic electronic properties of these elements by the use of DV-Xa molecular orbital method. It is found that the covalent bonding between neighboring atoms, namely the short range chemical interaction is very important to determine the valence band structure of transition element. The spin polarization in the transition metal cluster has been investigated and the mechanism of the magnetic interaction between the atomic spins has been interpreted by means of the spin polarized molecular orbital description. For heavy elements like 5d transition metals, the relativistic effects are found to be very important even in the valence electronic state. 

It is well known from Hartree-Fock studies of molecular systems, that it is very common to have problems of SCF convergence when studying open-shell systems similarly, convergence problems are not rare in the Hartre Fock treatment of spin-polarized crystals. A well-known technique for the solution of convergence problems, in the case of open-shell molecules, is the so-called level-shifting method [85] this approach has shown its effectiveness in the periodic HF context also, especially in the case of crystals containing transition elements. 

While the concentration dependence of the experimental fields are reproduced rather well by the theoretical fields (a phase transition to the BCC structure occurs around 65% Fe), the later ones are obviously too small. This finding has been ascribed in the past to a shortcoming of plain spin density functional theory in dealing with the core polarization mechanism (Ebert et al. 1988a). Recent work done on the basis of the optimized potential method (OPM) gave results for the pure elements Fe, Co and Ni in very good agreement with experiment (Akai and Kotani 1999). 

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