Harmonium atoms at weak confinements: The formation of the Wigner molecules.
The formation of the Wigner molecules in three-dimensional assemblies of equicharged particles upon weakening of harmonic confinements with spherical symmetry is investigated using five electronic states of the four-electron harmonium atom as a representative example. Numerical results of accurate explicitly-correlated calculations, carried out for a wide range of confinement strengths ω, reveal nonmonotonic convergence of the total energies and one-electron densities to those predicted by the formalism asymptotically exact at the ω→0 limit. The convergence rates are strongly state- and property-dependent, which implies the nonexistence of a single measure quantifying the extent of the formation of the Wigner molecule in a particular state of the harmonium atom. In light of these observations, it is concluded that, like in two dimensions, the emergence of the Wigner molecules in Coulombic systems confined by spherically symmetric harmonic potentials is a complex and gradual process that takes place over a range of confinement strengths spanning several orders of magnitude.
Institute of Physics, University of Szczecin, Wielkopolska 15, 70-451 Szczecin, Poland and Max-Planck-Institut für Physik komplexer Systeme, Nöthnitzer Strasse 38, D-01187 Dresden, Germany.
Jerzy
J
Cioslowski
Department of Physical and Quantum Chemistry, Faculty of Chemistry, Wrocław University of Technology, Wybrzez˙e Wyspiańskiego 27, 50-370 Wrocław, Poland.
Krzysztof
K
Strasburger