Relativistic effects on the hyperfine structures of2p4(3P)3p2Do,<

Abstract

The hyperfine interaction constants of the 2p 4 ( 3 P )3p 2 D o 3/2,5/2 , 4 D o 1/2−7/2 and 4 P o 1/2−5/2 levels in neutral fluorine are investigated theoretically. Large-scale calculations are carried out using the multiconfiguration Hartree-Fock (MCHF) and Dirac-Hartree-Fock (MCDHF) methods. In the framework of the MCHF approach, the relativistic effects are taken into account in the Breit-Pauli approximation using non relativistic orbitals. In the fully relativistic approach, the orbitals are optimized using the Dirac-Coulomb Hamiltonian with correlation models inspired by the non relativistic calculations. Higher-order excitations are captured through multireference configuration interaction calculations including the Breit interaction. In a third (intermediate) approach, the Dirac-Coulomb-Breit Hamiltonian matrix is diagonalized in a relativistic configuration space built with non relativistic MCHF radial functions converted into Dirac spinors using the Pauli approximation. The magnetic dipole hyperfine structure constants calculated with the three relativistic models are consistent and reveal unexpectedly large effects of relativity for 2 D o 5/2 , 4 P o 3/2 and 4 P o 5/2 . The agreement with the few available experimental values is satisfactory. The strong J-dependence of relativistic corrections on the hyperfine constants is investigated through the detailed analysis of the orbital, spin-dipole and contact relative contributions calculated with the non relativistic magnetic dipole operator.

Theoretical study of the isotope effects on the detachment thresholds ofSi−

“…The overall consistency between the so-deduced corrections, in particular in the cases where they account for a large fraction of the hyperfine constants, brings a new evidence that they yield useful estimates of relativistic effects. This is particularly interesting in the context of non-relativistic methods, as it is in general necessary to consider the impact of relativity on the results [33]. Tables IV, V and VI.…”

“…We compare the Breit-Pauli Configuration Interaction method (BPCI) [30], and the Relativistic configuration interaction method using the Pauli approximation (RCI-P) [34]. Such a comparison has recently been performed for excited states of fluorine [33], showing a good consistency between the two approaches. For differential effects like the electron affinity and its isotope shift, one has to strike a balance in the nonrelativistic approach as well as in the relativistic one.…”

Advanced multiconfiguration methods for complex atoms: I. Energies and wave functions

“…Predictions can be improved with expansions that take into account the atomic property under investigation. Applications that have been extensively investigated are spectrum calculations for all levels up to a designated excited level, allowed and forbidden transitions [143,148,197,198,54], isotope shifts [199,200,201,184,202,203], hyperfine structures [204,159,205,206], nuclear effects on transition rates and spectra [26,207], magnetic field-induced transitions [208,209,20], to name a few. A comprehensive list of relativistic calculations and theoretical studies can be found in the RTAM bibliography database [210].…”

“…This method, based on the use of a relativistic configuration interaction approach in the Pauli approximation, labelled RCI-P, provides an interesting way of checking the reliability of independent MCHF-BP calculations [153,159].…”

From atoms to biomolecules: a fruitful perspective

“…In the present contribution, we illustrate how relativistic corrections can be large in fluorine, despite its low atomic number (Z = 9). Table 1 reports the theoretical values of the magnetic dipole hyperfine constant A J for 2p 4 3p that are estimated using elaborate single-and double-multireference MCHF correlation models [23], together with the experimental value [158] for 2 D 5/2 o . The calculations are performed using the multiconfiguration Hartree-Fock (MCHF) and DiracFock (MCDF) methods.…”