Segmented Contracted Douglas–Kroll–Hess Adapted Basis Sets for Lanthanides

Abstract

Segmented contracted scalar-relativistic (23s16p12d6f)/[18s12p9d3f] all-electron basis sets for lanthanides La-Lu primarily for use in second-order Douglas-Kroll-Hess density functional calculations are presented. Atomic test calculations at the scalar-relativistic Hartree-Fock level reveal an accurate description of the first to fourth ionization potentials as well as low-energy d-f and d-p excitation energies; i.e., reference data obtained with optimized (34s28p22d16f) even-tempered basis sets are reproduced with mean absolute errors of 0.003 (IP1), 0.013 (IP2), 0.030 (IP3), 0.098 (IP4), 0.070 (d-f), and 0.018 (d-p) eV. Results of molecular test calculations are presented for the lanthanide trihalides LnX3 (Ln = La-Lu, X = F, Cl, Br, I) at the PBE0 hybrid density functional theory level. Compared to recently published basis sets of identical size, the sets proposed here show substantially smaller errors in the atomic test calculations as well as lower total energies and produce results of similar accuracy in the molecular calibration study.

Relativistic Pseudopotentials and Their Applications

“…It should be noted that this finding is not due to a PP defect, i.e., very similar results are obtained in relativistic AE calculations using DKH2 Hamiltonian [113]. Therefore, Dolg et al concluded that the shorter Am III -S (or I) compared to the Eu III -S (or I) bonds should not be interpreted as a higher covalency in the former systems, but rather as a consequence [119] and the SPP ACPF [115] level in comparison to experimental results [116] of the so-called delocalization error of many commonly used density functionals [114] as well as the underestimation of the repulsive interaction of electrons with equal spins within the f shell (no DFT functional adjusted to f elements) [109].…”

Does the 4f-shell contribute to bonding in tetravalent lanthanide halides?

“…1-5 The first theoretical investigation of lanthanide trihalides at ab initio level was from Dolg, and later, Dolg and Cundari et al have reported the density functional theory (DFT) and multicongfiguration self-consistent-field method (MCSCF) results with explicit treatment of 4f. [6][7][8] In addition to important applications in various fields of chemistry and physics, [9][10][11][12][13] the molecular properties of lanthanide (Ln) complexes have been the subject of intense discussions in basic science. Besides +3 oxidation state, the +2 state plays an important role for Sm, Eu, and Yb, 14 while +4 is important for Ce, Pr, and Tb.…”

Absolute NMR shielding scales and nuclear spin–rotation constants in 175LuX and 197AuX (X = 19F, 35Cl, 79Br and 127I)

“…[35][36][37] In the CCSD(T) calculations, it was practically impossible to use the larger unc-ANO-RCC basis set, due to the large number of electrons in the molecules studied. Hence, in the CCSD(T) calculations, we used the uncontracted versions of the all-electron scalar relativistic Douglas-Kroll-Hess (denoted as unc-Cologne DKH2) basis set for lutetium (Lu), 38 double-ζ polarized Douglas-Kroll-Hess (denoted as unc-DZP-DKH) basis set for gold (Au), 39 and uncontracted augmented double-ζ polarized (denoted as unc-ADZP) basis sets for the halogen atoms. [40][41][42] We note that there are very few small all-electron basis sets available for the lutetium and gold atoms; therefore, at the CCSD(T) level, the above described literature basis sets were chosen and uncontracted to ensure increased flexibility in the region close to the nucleus.…”