EGAS41 - Swansea University

41 st EGAS CP 84 Gdańsk 2009
Exploration of possibilities of quasirelativistic Breit-Pauli
approach within oxygen isoelectronic sequence
O. Rancova 1,∗ , P. Bogdanovich 1 , L. Krasauskas 2
1 Institute of Theoretical Physics and Astronomy of Vilnius University,
A. Goštauto st. 12, LT-01108 Vilnius, Lithuania
2 Faculty of Physics, Vilnius University, Sauletekio al. 9, Vilnius LT-10222, Lithuania
∗ Corresponding author: olga@itpa.lt,
Calculations of energy spectra of atoms and ions within Breit-Pauli approach have certain
advantages: the energy spectra are obtained within LS-coupling comfortable for
interpretation of the experimental data and the methods for extended calculation of the
correlation corrections are well- developed and require moderate computational resources.
However, application of the traditional Breit- Pauli approach is limited for heavy atoms
and highly charged ions. The possibilities to extend the framework of Breit-Pauli approach
by using the quasirelativistic radial orbitals are investigated within the oxygen
isoelectronic sequence (Z = 9 − 34).
The quasirelativistic Hartree-Fock equations have been formed anew seeking to avoid
any unjustified simplifications and solved taking into account the finite size of the atomic
nucleus [1]. The total energy corrections of Breit-Pauli formalism are rewritten in correspondence
with the properties of the quasirelativistic radial orbitals [2]. The calculations
are performed applying the configuration interaction technique on the basis of the transformed
radial orbitals with variable parameters. In order to evaluate the influence of
the quasirelativistic radial orbitals on the accuracy of the results the same calculations
are reduplicated within the usual Breit-Pauli approach on the basis of non-relativistic
functions taking into account the correlation effects in the same way as with the quasirelativistic
functions.
The energy levels of the n = 2 complex of O-like ions as well as transition characteristics
have been calculated by two mentioned methods. The transformed radial orbitals
have been formed using the excitations into the virtual states with 4 ≤ n ≤ 8 and all
possible values of l and configuration interaction have been performed within this basis.
The results obtained are compared with the available experimental data [3]. The
relative accuracies of the calculated values to the experimental ones are compared for
two approaches used and plotted for every energy level throughout the isoelectronic sequence.
The comparison of the results shows how relative deviations of the energy values
calculated within the usual Breit-Pauli approach increase as ion nuclear charge grows
while relative deviations of the energies calculated within the quasirelativistic Breit-Pauli
approach change weakly within the explored isoelectronic sequence.
Acknowledgment
This work is partially supported by the European Communities under the FP7 contract of
Association between EURATOM/LEI FU07-CT-2007-00063.
References
[1] P. Bogdanovich and O. Rancova, Phys. Rev. A 74, 052501 (2006)
[2] P. Bogdanovich and O. Rancova, Phys. Scr. 78, 045301 (2008)
[3] NIST Atomic Spectra Database (version 3.1.5), [Online]. National Institute of Standards
and Technology, Gaithersburg, MD.
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