Self-consistent Dirac-Slater calculations for molecules and embedded clusters

The basis of self-consistent local density theory used in the fully relativistic Dirac–Slater model is briefly reviewed. Moment-polarized extensions of theory are developed to treat open-shell systems by lifting the pair-wise Kramers degeneracy. The discrete variational method is used to calculate one-electron energies and charge and magnetization densities of a series of rare-earth trihalides. The theoretical binding energies compare very well with recent gas-phase photoelectron spectra of Berkowitz et al. The von Barth–Hedin exchange and correlation potential produces energies which are significantly better, compared to simpler exchange-only models. Embedded molecular cluster studies on actinide compounds are reported, with particular emphasis on the AcO2 dioxides. Single-particle energy densities of states (DOS) and magnetization DOS are presented, along with an analysis of effective atomic configurations in the solid. Trends in these quantities with actinide atomic number are noted. In contrast to the semicore nature of rare-earth 4f electrons, the actinide 5f levels are seen to be active participants in bonding interactions.