Broken symmetry approach

Deuterium diffusion was studied in VDX, where 0.4 < x < 0.6, by means of 2H NMR measurements.599 1H and 51V spin-lattice relaxation times for TaV2Hx, where x < 0.18, were consistent with two co-existing proton-jump processes.600 3H, 2H and 51V spin-lattice relaxation times were also determined for NbVCrHo.3, NbVCrD0.3g and NbV 14Cro.6Ho.6 in the temperature range 11-424 K.601 A DFT/broken symmetry approach has been used to study exchange... 

Despite the publication of these papers, as was indicated in the introduction, most of the later publications have focused on the calculation of dinuclear complexes employing the broken-symmetry approach proposed by Noodleman et al. In this approach the J value involves the calculation of the energy difference between the high-spin state and a low-spin solution that corresponds to a broken symmetry wavefunction in the case of symmetric homodinuclear complexes. From now on, it will be employed the expressions for the Hamiltonians indicated in Eqs. (1) and (2) Eq. (3) was kept for historical reasons. A general expression, (see Eq. 4) can be proposed for any dinuclear complex using the original broken-symmetry approach proposed by Noodleman [26] ... 

The current calculations, which are not yet routine, but which can now be performed on relatively simple computers, are based on DFT models for the description of the MOs of magnetic molecules, and on the so-called broken-symmetry approach, first suggested by Noodleman in 1981. ... 

The broken-symmetry approach was developed within the framework of unrestricted Hartree-Fock theory or spin-polarized density functional theory, i.e., Xa theory. " It is based on the assumption that the energy difference between the singlet and triplet states resulting from the interaction between two 5 = 1/2 spin centers is given by ... 

C. van Wullen. Broken symmetry approach to density functional calculation of magnetic anisotropy or zero field splittings for multinuclear complexes with antiferromagnetic coupling. /. Phys. Chem. A, 113 (2009) 11535-11540. 

The most widely applied approximation to extract / within a single determinant description of the spin states is the so-called Broken Symmetry approach which uses two determinants ... 

Broken symmetry approach. The magnetic coupling of three binuclear TM complexes has been studied with DFT. The following results were obtained for the HS and BS determinants, (a) Calculate the magnetic coupling parameter J with the Yamaguchi equation (Eq. 4.85) and compare the outcomes to the alternative relations of Noodleman (Eq.4.86) and Ruiz (Eq.4.87). 

Ghosh R, Seal P, Chakrabarti S (2010) Role of p-conjugation in influencing the magnetic interactions in dinitrenes a broken symmetry approach. J Phys Chem A 114 93-96... 

The magnetic exchange coupling can also be calculated using Density Functional Theory (DFT) based on the broken symmetry approach, developed by Noodleman [24]. The formalism for a model with two interacting metal centers A... 

Table 6.7 Parameters from DFT calculations for the calculation of the magnetic exchange coupling via the broken symmetry approach... 

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