Lanthanides and Actinides

The application of quantum chemistry to systems containing atoms of the lanthanide (57La 71Lu) and/or actinide (90Th 103Lr) series is a considerable challenge and has been attempted only by a comparatively small number of researchers. Several complications, some of which will be described in the following, prevent standard quantum chemical approaches from being successful in this field in all respects. However, although no entirely satisfactory calculations on these systems can be performed at present, the rapid development of computer technology as well as quantum chemistry methodology and software made considerable progress possible in the 1990s and will certainly permit accurate investigations of compounds containing lanthanides and actinides to be made in the near future. The available relativistic electronic structure calculations for lanthanideand actinide-containing molecules were briefly reviewed by Pyykkö1 in 1987. Extensive reviews for lanthanide and actinide compounds have been published more recently by Dolg and Stoll2 and Pepper and Bursten,3 respectively. Calculations for lanthanideand actinidecontaining molecules as well as some related transition metal systems have been summarized by Balasubramanian.4 Some information is also available from several reviews of relativistic quantum chemistry, e.g., by Pyykkö5 or Malli.6 A bibliography of relativistic quantum chemical studies collected by Pyykkö7 is available on the Internet. The remainder of this article discusses some general points important for quantum chemical studies of systems containing lanthanides and actinides, then briefly summarizes the quantum chemical methods applied so far to study f element systems, and finally focusses on a few characteristic examples. Owing to the limited space available here many interesting investigations have been omitted and only a broad overview can be given. The reader is referred to the above-mentioned reviews for a more complete set of citations. 2 GENERAL