Crystal field configuration interaction

The Wyboume crystal field parameters B (f, f), B (d, d), and Bjj(f, d), which describe the interaction due to the presence of the ligands onto the electrons of the lanthanide center. They are deduced from the ligand field energies and wave functions obtained from Kohn—Sham orbitals of restricted DFT calculations within the average of configuration (AOC) reference by placing evenly n — 1 electrons in the 4f orbitals and one electron in the 5d.33... 

Multipole analysis with high-resolution X-ray data for [Ni(thmbtacn)]2+ was carried out to determine the electron configuration in the C3 symmetry-adapted orbitals of the Ni ion, confirming a higher occupancy of the crystal field-stabilized t2g orbitals relative to the destabilized eg orbitals. This is interpreted in terms of a predominantly ionic metal-ligand interaction.1424... 

Quantum Systems in Chemistry and Physics is a broad area of science in which scientists of different extractions and aims jointly place special emphasis on quantum theory. Several topics were presented in the sessions of the symposia, namely 1 Density matrices and density functionals 2 Electron correlation effects (many-body methods and configuration interactions) 3 Relativistic formulations 4 Valence theory (chemical bonds and bond breaking) 5 Nuclear motion (vibronic effects and flexible molecules) 6 Response theory (properties and spectra atoms and molecules in strong electric and magnetic fields) 7 Condensed matter (crystals, clusters, surfaces and interfaces) 8 Reactive collisions and chemical reactions, and 9 Computational chemistry and physics. 

We discussed above the analysis of core-level spectra from cuprates which contain only a single hole in the d-band per Cu ion. This makes an irrelevant parameter within an impurity model. However, analysis can also be carried out for systems where [7dd plays a significant role. This is illustrated by the analysis of the core-level spectrum of LaCoOj carried out within the impurity model (Chainani et al, 1992). This oxide is modelled by the (CoOg) cluster with the transition-metal ion being formally in the 3 + oxidation state and in an octahedral crystal field. One has to therefore take into account interactions between various configurations such as d >, d Z, > >. ... 

Jahn-Teller Effect. With the exception of d3, d5, and d8 configurations, the ground state in an octahedral crystal field is still orbitally degenerate. Some of this degeneracy is removed by the spin-orbit interaction. 

Consider a dn configuration present in a crystal field that leaves the ground state nondegenerate except for spin. The ground state then consists of (25+ l)-spin states and the effect of the spin-orbit interaction plus the magnetic field can be computed using first- and second-order perturbation theory. If we take as the perturbation operator... 

The d5 configuration presents a special problem in that it is a 6S state, and Eqs. (72), (75), and (76) predict that gz=gx=gy =2.0023 and D = E=0 for any crystal field. Experimentally, these ions have g values close to 2.0023 but never exactly. Further these ions have appreciable values for D. It has been found necessary to use configuration interaction and higher-order-perturbation theory (14, 19) to account for this. 

Model Hartree-Fock calculations which include only the electrostatic interaction in terms of the Slater integrals F0, F2, F and F6, and the spin-orbit interaction , result in differences between calculated and experimentally observed levels596 which can be more than 500 cm-1 even for the f2 ion Pr3. However, inclusion of configuration interaction terms, either two-particle or three-particle, considerably improves the correlations.597,598 In this way, an ion such as Nd3+ can be described in terms of 18 parameters (including crystal field... 

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