Multiconfiguration Hartree-Fock Results with Breit-Pauli Corrections for Transitions in the Carbon Sequence

Abstract

The Multiconfiguration Hartree-Fock method, extended to include relativistic effects in the Breit-Pauli approximation (MCHF + BP), has been used to determine wavefunctions for the different LSJ states of the 2 s 2 2 p z ground and the 2 s 2 p 3 excited configurations of the carbon isoelectronic sequence for nuclear charges, Z , up to thirty. Term energies and fine-structure splitting have been predicted from these wavefunctions, as well as transition probabilities. The latter include the forbidden transitions, electric quadrupole (E2) and magnetic dipole (MI), between the levels of the ground configuration, as well as the allowed 2 s 2 2 p 2 -2 s 2 p 3 transitions. In this paper our results are reported and typical transitions compared with those from other theories as well as those from observation, as available. For Z up to about 20, our energy levels are generally in better agreement with observation than those from other theories. ~ a Garatang [ 181 ' Kastner et al. 191 Physica Scripta 32 BdlUJa and Doyle (101

Atomic Data and Spectral Line Intensities for S xi

“…Also, Froese Fischer & Saha (1985) agree with the present calculations for the allowed n ¼ 2 transitions. Since these three data sets were obtained using three different approximations, and adopt the largest set of configurations in the wave function expansion, the agreement indicates that the present results are very accurate, within 10%, which is the upper limit of the differences in these three data sets.…”

“…In general, a limited atomic model is expected to provide less accurate results. Froese Fischer & Saha (1985) used Notes.-Energies are in cm À1 . Experimental energies are from Fuhr et al 1999. the multiconfiguration Hartree-Fock method, extended to include relativistic effects in the Breit-Pauli approximation, and included a large number of configurations in their computation.…”

CHIANTI - an atomic database for emission lines

“…Experimental energies come from the NIST database and have been used to calculate transition wavelengths. Oscillator strengths and A values are from the calculations of Froese- Fischer & Saha (1985).…”

Contribution to the theoretical investigation of electron and photon interaction with carbon atom and its ions

“…Detailed structure calculations have been reported for the astrophysically important transitions [1][2][3][4]. More extensive theoretical and experimental reported works exist for the carbon ions.…”

“…We report a new set of R-matrix calculation intended specifically to investigate the role of including configuration interaction (CI) wave functions both in the target state expansion and in the (N+1)-electron quadratically integrable function expansion. Target-atom states were computed using the Hartree-Fock ground configuration 2s 2 2p 2 plus the near-degenerate configurations 2s2p 3 and 2p 4 . In addition, for consistency with the virtual excitation pattern used for scattering wave functions, all virtual excitations of 2s 2 2p…”