High-spin structure

MnAs exhibits this behavior. It has the NiAs structure at temperatures exceeding 125 °C. When cooled, a second-order phase transition takes place at 125 °C, resulting in the MnP type (cf. Fig. 18.4, p. 218). This is a normal behavior, as shown by many other substances. Unusual, however, is the reappearance of the higher symmetrical NiAs structure at lower temperatures after a second phase transition has taken place at 45 °C. This second transformation is of first order, with a discontinuous volume change AV and with enthalpy of transformation AH. In addition, a reorientation of the electronic spins occurs from a low-spin to a high-spin state. The high-spin structure (< 45°C) is ferromagnetic,... 

Fig. 2. Relative energy differences between the spin states of [Fe2] 1, for each spin state optimized structures denoted opt as well as for single-point calculations on the optimized high-spin structure denoted as single point, where the energy of the closed-shell spin restricted state has arbitrarily been set to zero.

Fig. 3. Relative energies for spin states of the [FeJ cluster 2 on optimized structures of spin symmetry given (left panel) as well as single points at the high-spin structure (right panel). The BS solution is not displayed.

The Total Spin Expectation Value S2 and Selected Local (SzA), (Sa), and (Sa SB) Values of the [Fe2] Cluster 1 Obtained with Mulliken Projection Operators are Given for Local Decomposition Schemes According to Mayer and to Clark and Davidson for Single-Point Calculations on the BP86/M/TZVP Optimized High-Spin Structure... 

In order to explore the possibility of such effects in the y plane as a function of the proton number we have studied the high spin structure of Lu which has two protons and two neutrons more than 159Tm. In this case the tt9/2 [514] and possibly the tt7/2+[404] orbitals would be predominantly populated. The former of these may be a new candidate for such a signature inversion. 

This paper is necessarily a very abbreviated survey, but we hope we have demonstrated by these few examples that Coriolis coupling and rotational alignment play an important part in high-spin structures of odd-odd nuclei. This can be true for nuclei near closed... 

Arylamines display electronic properties that are favorable for materials science. In particular, arylamines are readily oxidized to the aminium form, and this leads to conductivity in polyanilines, hole-transport properties in triarylamines, stable polyradicals with low energy or ground-state, high-spin structures, and the potential to conduct electrochemical sensing. The high yields of the palladium-catalyzed formation of di- and triarylamines has allowed for ready access to these materials as both small molecules and discrete oligomeric or polymeric macromolecules. 

Properties such as conductivity of doped polymers and magnetism of high-spin structures are bound to the stability of radical and/or ion sites. Various attempts to stabilize doped materials on a molecular basis have been considered, e.g. via the introduction of polarizable sulfur substituents, or by methods of processing such as immobilization in films or isolation in matrices. 

The high spin structure (open crevice) is converted into a low spin structure (closed crevice) under pressure. The activation volume for this process is +20 ml. This is characteristic for a dissociative mechanism (13). A possible model system for this process has recently been studied (14). 

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