The angular overlap model extended for two-open-shell f and d electrons

Abstract

We discuss the applicability of the Angular Overlap Model (AOM) to evaluate the electronic structure of lanthanide compounds, which are currently the subject of incredible interest in the field of luminescent materials. The functioning of phosphors is well established by the f-d transitions, which requires the investigation of both the ground 4f n and excited 4f nÀ1 5d 1 electron configurations of the lanthanides. The computational approach to the problem is based on the effective Hamiltonian adjusted from ligand field theory, but not restricted to it. The AOM parameterization implies the chemical bonding concept.Focusing our interest on this interaction, we take the advantages offered by modern computational tools to extract AOM parameters, which ensure the transparency of the theoretical determination and convey chemical intuitiveness of the non-empirical results. The given model contributes to the understanding of lanthanides in modern phosphors with high or low site symmetry and presents a non-empirical approach using a less sophisticated computational procedure for the rather complex problem of the ligand field of both 4f and 5d open shells.

On exchange coupling and bonding in the Gd2@C80 and Gd2@C79N endohedral dimetallo-fullerenes

“…The current versions of LF methods, dedicated to f or d shells suffer from a tacit drawback, the holohedrisation effect, marking the incapacity to account correctly the asymmetric environments. The multi-shell LF developed recently by us [36] is applied here for the description of the highly polar environment felt by a lanthanide ion.…”

“…Actually, in this circumstance, the relative difference is not an entirely LF potential element, including the f-d gap, as intrinsic feature of the ion to which LF shifts are added. The odd components (k = 1, 3, 5) are appearing in the f-d diagonal block that carries the modelling beyond the holohedrisation limits [36]:Ĥ fd LF = k=1, 3,5 …”

“…The artificial effect of holohedrisation can be encompassed designing an extended LF scheme with both odd and even basis components insofar as the off-diagonal block includes the g × u = u asymmetric components. We recently presented a two-shell extended LF model based on d and f orbitals [36], which needs to be called for the account of the presented case. Indeed, we face a rather visible polarisation of the electrostatic potential, with fullerene as a negatively charged A ligand and the companion metal ion as a positive charge B, acting reversely to the usual ligands.…”

Electronic fine structure calculation of metal complexes with three-open-shell s, d, and p configurations

“…7) is always limited by symmetry constraint [59]. In the present studies of aqua complexes of transition metal ions (see Introduction) belonging to the high symmetrical T h point group (see Fig.…”

“…1), only the parameter B 4 0 (dd) is significant (Eq. 9) [59]. The s and p orbitals belong to the a g and the threefold degenerate t u irreducible representations (irreps) of the T h point group, respectively, i.e., their energies are not split by the ligand field effect.…”