STABLE ELECTRONIC CONFIGURATION MODEL AND PROPERTIES OF RARE EARTH METALS AND THEIR COMPOUNDS.

The stable electronic configuration model was originally proposed by Samsonov in 1965 and since then a large number of work has been dome to study the applicability of the model in solving many fundamental and applied problems concerning materials. According to the model during the formation of condensed solid state valence electrons can be divided into localised and nonlocalised parts. The localised fraction of these electrons forms a fairly broad spectrum of configurations which differ in their energetic stabilities, so that along with the very stable configurations there appear some, which are less stable or even unstable. Between the stable configurations and the non-localized fraction of the valence electrons there occur exchanges which are responsible for the bonds between pairs of stable configurations.