Irreducible interaction between ions

The orbital triplet states (transforming as the Ti or Ty irreducible representations) interact with crystal lattice vibrations, and this interaction affects also the SO splitting of these states. From the computational point of view, the effects of interaction between the electronic levels arising from the orbital triplet and surrounding ions can be modeled easier if each orbital triplet would be considered individually, without explicit treatment of mixture with electronic states from other... 

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