Fyzikální ústav Akademie věd ČR

Calculation of the crystal field parameters (CFP) of the rare-earth (RE) ions in solids is a formidable problem and until recently no robust ab-initio method to calculate them was available. The main problem is that in most approaches the 4f electrons of RE are allowed to interact with the nonspherical electron density they create themselves and this false selfinteraction completely distorts the crystal field. The second problem is that no ab-initio method is capable to determine correctly hybridization of the 4f levels with ligand electron states.