Spin density studies

It is not possible to give here a complete review of DMol applications, so only a non-systematic selection of applications is mentioned here. Applications to chemical reactions have been studied by Seminario, Grodzicki and Politzer [10]. Buckminster-fullerenes have been studied by various groups [11] including also nonlinear optical properties [8] and the geometrical structure of Cs4 [13]. Cluster model studies of surfaces with adsorbates are reported in [14-17]. Cluster models for point defects in solids, in particular spin density studies of interstitial muon can be found in [18,19]. Spin density studies of molecular magnetic materials are in ref [20]. Polymers have been studied by Ye et al [21]. 

It is clear that an ah initio calculation of the ground state of AF Cr, based on actual experimental data on the magnetic structure, would be at the moment absolutely unfeasible. That is why most calculations are performed for a vector Q = 2ir/a (1,0,0). In this case Cr has a CsCl unit cell. The local magnetic moments at different atoms are equal in magnitude but opposite in direction. Such an approach is used, in particular, in papers [2, 3, 4], in which the electronic structure of Cr is calculated within the framework of spin density functional theory. Our paper [6] is devoted to the study of the influence of relativistic effects on the electronic structure of chromium. The results of calculations demonstrate that the relativistic effects completely change the structure of the Or electron spectrum, which leads to its anisotropy for the directions being identical in the non-relativistic approach. 

A practical ramification of this rule is utilized in segregation studies. The most obvious way to study segregation by NMR/MRI is to use two different types of beads, one that is NMR-visible and the other not. However, size segregation studies can be performed by simply using two different sizes of NMR-visible particles because they have different overall spin densities, for the reason stated above. Therefore, the image intensity will depend on the relative concentration of each particle in a voxel. 

Two-channel MaxEnt techniques have also been used in the study of magnetization and spin densities [34, 35] and to interpret unpolarised neutron diffraction data [36]. 

Baron, V., Gillon, B., Kahn, O. et al. (1993) Spin density in a bimetallic magnetic chain MnCu(pba)(H20)3. 2H20 a polarised neutron diffraction study, Mol. Cryst. Liqu. Cryst., 233, 247-256. 

Zheludev, A., Bonnet, Luneau, D. et al. (1995) The spin density in an imino nitroxide free radical a polarized-neutron study, Physica B, 213-214, 268-271. 

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