ИСТИНА

A general approach to the description of effective states of heavy atoms in molecules and solids in terms of fractional-occupancy relativistic configurations in the frames of the new Atoms-in-Compounds (AiC) concept [1] and relativistc DFT is discussed. This approach is based on the analysis of molecular one-electron density matrices in the vicinity of heavy nuclei and the simulation of the basic features of these entities in the calculations of the corresponding free (or confined in a spherical cavity) heavy atom. The resulting configurations are related, at least in principle, to certain measurable (spectral) properties of the compounds. A series of applications to simple compounds of early transuranium elements (Pu-Cf) and superheavy elements (SHE) 112-114 is presented. Qualitatively different occupation patterns of effective SHE atoms and their formal lighter homologues (Hg-Pb) in the molecules of their simple binary compounds reflect the radical differences between their chemical properties. The results are compared to those obtained by the projection technique [2]. The uselessness of non-relativistic (or scalar relativistic) configurations for understanding the essential chemistry of the mentioned SHE is underlined. In contrast, scalar relativistic model provides a reliable and transparent interpretation of peculiarities in the dependencies of molecular properties on the actinide atomic number.