Relativistically parameterized extended Huckel calculations. 10. Lanthanide trihalides

Abstract

The REX relativistically parameterized extended Huckel method is used to study the electronic structure of lanthanide trihalide molecules. All valence orbitals are described in terms of double-zeta Slater functions, with the atomic orbital parameters being determined by a least-squares fitting to published relativistic (Dirac- Fock) radial densities. Comparisons of orbital energies to experimental values are made and various trends are discussed. Ab initio all-electron calculations at the self-consistent field level and as a function of molecular geometry are reported for LaH3, LaF3, and LaCl3. While LaH3 and LaF3 are calculated to be pyramidal, LaCl3 is calculated to be planar.