posted on 2024-01-01, 16:03authored byChristian Tantardini, Roberto Di Remigio Eikås, Magnar Bjørgve, Stig Rune Jensen, Luca Frediani
New techniques in core–electron spectroscopy are
necessary
to resolve the structures of oxides of f-elements
and other strongly correlated materials that are present only as powders
and not as single crystals. Thus, accurate quantum chemical methods
must be developed to calculate core spectroscopic properties in such
materials. In this contribution, we present an important development
in this direction, extending our fully adaptive real-space multiwavelet
basis framework to tackle the four-component Dirac-Coulomb-Breit
Hamiltonian. We show that multiwavelets can reproduce one-dimensional
grid-based approaches. They are however a fully three-dimensional
approach which can later be extended to molecules and materials. Our
multiwavelet implementation attained precise results irrespective
of the chosen nuclear model, provided that the error threshold is
tight enough and that the chosen polynomial basis is sufficiently
large. Furthermore, our results confirmed that in two-electron species,
the magnetic and Gauge contributions from s-orbitals
are identical in magnitude and can account for the experimental evidence
from K and L edges.