Crystal configuration interaction model

Spin-correlated crystal field 276 4.5. The configuration interaction model ... 

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... 

The shape resonances have been described by Feshbach in elastic scattering cross-section for the processes of neutron capture and nuclear fission [7] in the cloudy crystal ball model of nuclear reactions. These scattering theory is dealing with configuration interaction in multi-channel processes involving states with different spatial locations. Therefore these resonances can be called also Feshbach shape resonances. These resonances are a clear well established manifestation of the non locality of quantum mechanics and appear in many fields of physics and chemistry [8,192] such as the molecular association and dissociation processes. 

However, applying the same model to the high-pressure results for Sm +, extreme deviations were encountered. The authors attributed these deviations to a breakdown of the spin-correlated crystal-field model for Sm " ". As the reason for this failure, configuration interactions with the 4f 5d configuration were determined. These interactions are expected to be much stronger for Sm " ", because the energy of the excited configuration is much lower (at about 20 000 cm ) than in the case of Eu + (at about 50 000 cm ). 

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