Lanthanide and actinide molecules

K. Balasubramanian, Relatiznstic effects and electronic structure of lanthanide and actinide molecules 29... 

Balasubramanian K (1994) Relativistic effects and electronic structure of lanthanide and actinide molecules. In Gschneider KA, Eyring L, Choppin GR, Lander GH (eds) Handbook on the physics and chemistry of rare eeuths, vol 18. Elsevier, Amsterdam, pp 29-158... 

Finally, a review of relativistic effects and the electronic structure of lanthanide and actinide molecules has recently been published by Balasubramanian (1994) in this Handbook Series (Vol. 18, ch. 119). Topics treated in more detail by Balasubramanian, e.g. the effects of the lanthanide contraction on the 5d transition metals, have been kept rather brief in the present article. Although it is not possible to completely avoid overlap with the review by Balasubramanian, we hope that the reader still benefits from the present contribution. 

RELATIVISTIC EFFECTS AND ELECTRONIC STRUCTURE OF LANTHANIDE AND ACTINIDE MOLECULES... 

Theoretical methods for lanthanide and actinide molecules 3.1 Ab initio techniques... 

Ab initio methods for lanthanide and actinide molecules are mostly based on the effective core potential (ECP) method, especially if the molecules in question have several heavy atoms. The philosophy of the ECP method is to replace the chemically unimportant core electrons by an effective core potential and treat the remaining valence electrons explicitly. There are several techniques to derive RECPs which we now briefly describe and refer to the reviews by Christiansen et al. (1985), Krauss and Stevens (1984), Balasubramanian and Pitzer (1987) for further details. 

The semiempirical relativistically parametrized extended Hiickel scheme developed by Pyykkd and Lohr was one of the first methods at hand to investigate the electronic structure of polyatomic lanthanide and actinide molecules, albeit only in a rather approximate way. Since this is an effective one-particle model, it is possible to discuss quantities... 

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