Ab Initio Studies on the Structures and Vibrational Frequencies of Rare Earth Fluorides LnF<i>_n</i> (Ln = Er, Tm; <i>n</i> = 1, 2, 3) and Their Positive Ions and an Assessment of Their Ionization and Dissociation Energies

Abstract

Hartree−Fock and second-order Møller−Plesset calculations are reported of the structural and vibrational parameters of some rare earth fluorides LnFn neutrals and LnFn+ ions, where Ln is erbium and thulium and n = 1, 2, and 3. Quasi-relativistic pseudopotentials developed by Dolg et al. were applied for a description of the core electrons of the lanthanide atoms. A planar D3h structure resulted from geometry optimization at both levels of calculation for the ground state of erbium and thulium trifluorides. The vertical and adiabatic ionization energies of LnFn+ are reported and Ln−F bond dissociation energies D0(LnFn-1−F) evaluated. These quantities are compared to available experimental data.