Some Trends in Relativistic and Electron Correlation Effects in Electric Properties of Small Molecules

Abstract

Abstract Trends in the relativistic and electron correlation effects in properties of molecules containing a heavy metal element are discussed. Numerical results analyzed in this paper have been mostly obtained by the Douglas–Kroll–Hess quasi-relativistic approach combined with the Coupled Cluster method. We discuss dipole moments and static electric dipole polarizabilities of diatomic molecules, like fluorides of the Ia and Ib group elements (RbF, CsF, and FrF; CuF, AgF, and AuF), coinage–aluminium intermetallic molecules (CuAl, AgAl, and AuAl) and group IVa elements oxides (GeO, SnO, and PbO). Trends in each group of molecules were related to relativistic effects in the heavy metal element ionization potential, electron affinity and the dipole polarizability. The relativistic shrinking of the electron density is also considered. Related topics are the bond dissociation energies of selected diatomic molecules and interaction energies in CuOH2, AgOH2, AuOH2, in CuSH2, AgSH2, AuSH2 and in CuNH3, AgNH3 and AuNH3. Interaction energies are interpreted in terms of the charge transfer mediated by the lone pair of the ligand. It is linked with relativistic increase of electron affinities of the coinage metal elements. Long-range terms are affected by relativistic changes of their polarizabilities and ionization potentials.