Ab initio averaged relativistic effective core potentials, spin–orbit operators, and valence basis sets are reported for the fourteen lanthanide elements Ce through Lu in the form of expansions in Gaussian-type functions. Gaussian basis sets with atomic orbital coefficients for low energy states of each atom are also tabulated. Hartree–Fock orbital energies calculated in conjunction with the relativistic effective core potentials using the j-j coupling scheme agree to within 10% of those due to numerical all-electron Dirac–Fock calculations. Excitation energies, ionization potentials, and spin–orbit splittings are compared to all electron, energy-adjusted effective core potential, and experimental results.

The mechanism for the quenching of surface states of GaAs by adsorbed elemental Se is studied using atomic clusters in ab initio Hartree–Fock calculations. Both the Ga- and the As-terminated surfaces are tied off with Se atoms in a 2×1 reconstruction. The most stable structure is established as two Se atoms bridging two As atoms. It is found that after termination of Ga and As dangling orbitals with H atoms and passivating the surface with Se, the density of surface states in the bandgap region is appreciably reduced.

Ab initio Hartree-Fock calculations are reported for the chemisorption of K on Ag using three different types of clusters to model the system. Geometry optimization is done in 4 degrees of freedom. It is found that since there is an absence of complete charge transfer between the adsorbate and substrate, the interaction can be interpreted as being predominately covalent in nature.

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