Fine-structure energy levels, oscillator strengths and lifetimes in Mn XIII

Abstract

We have performed large scale CIV3 calculations of excitation energies from ground state for 98 fine-structure levels as well as of oscillator strengths and radiative decay rates for all electric-dipole-allowed and intercombination transitions among the fine-structure levels of the terms belonging to the (1s 2 2s 2 2p 6 )3s 2 3p, 3s3p 2 , 3s 2 3d, 3p 3 , 3s3p3d, 3p 2 3d, 3s3d 2 , 3s 2 4s, 3s 2 4p, 3s 2 4d, 3s 2 4f and 3s3p4s configurations of Al-like manganese. These states are represented by very extensive configuration-interaction (CI) wavefunctions obtained with the CIV3 computer code of Hibbert. The important relativistic effects in intermediate coupling are incorporated by means of the Breit-Pauli Hamiltonian. In order to keep our calculated energy splittings as close as possible to the experimental values, we have made small adjustments to the diagonal elements of the Hamiltonian matrices. Our calculated excitation energies, including their ordering, are in excellent agreement with the available experimental results. From our radiative decay rates, we have also calculated radiative lifetimes of some fine-structure levels. Differences between our calculated lifetimes and those of Froese Fisher et al (2006 At. Data Nucl. Data Tables 92 607) for several fine-structure levels are discussed.

New atomic data for Ge XX

“…Our ab initio calculation, 'Present (a)', is in good agreement with the experimental and theoretical results complied by NIST, except for the levels 3s3p 2 ( 2 P 1/2 , 2 S 1/2 ), for which our calculated positions of these two levels to be reversed compared with those of NIST . This was previously noted by Gupta and Msezane [10] when comparing the ab initio MCHF levels of Froese Fisher et al [11] with NIST. The wave functions for the levels 3s3p 2 ( 2 P 1/2 ) and 3s3p 2 ( 2 S 1/2 ) exhibit very strong configuration mixing (55% and 42%), and in a simple ab initio calculation it is difficult to represent that mixing sufficiently accurately.…”

Multireference Møller–Plesset perturbation theory results on levels and transition rates in Al-like ions of iron group elements

“…The observation along the isoelectronic sequence of line intensity anomalies due to level mixing underlines the need for detail in the description of Al-like ions [54]. Gupta and Msezane have treated a selection of elements using the CIV3 code with a large number of configurations [4,5,[7][8][9][10][11][12]15]. Compared with all such earlier works, we expect higher accuracy than has been available before, and that from ab initio calculations, in contrast to earlier calculations (like those by Fawcett [17] who used a version of the Hartree XR Cowan code [55]) that involved the scaling of parameters to match the experimental level structure.…”

“…A second electron in the valence shell introduces massive complications; while experiment can reach the same accuracy as for one-electron spectra, theory has been struggling. Calculations of Al-like ions sometimes have been extensive, but have covered only a single element at a time [3][4][5][6][7][8][9][10][11][12][13][14][15], while others sometimes employed rather few configurations when tabulating results for a full isoelectronic sequence. For calculations of a sequence of ions along the Al sequence, see, for example [16][17][18][19][20][21][22].…”

Effects of valence-valence, core-valence, and core-core correlations on the fine-structure energy levels in Al-like ions

“…Many ab initio calculations using a wide range of different methods * gjiang@scu.edu.cn have also been done for calculating fine-structure energy levels and lifetimes. To mention just a few, fine-structure energy levels in Si II [8] and Al I-Fe XIV [9] have been calculated using the multiconfiguration Hartree-Fock (MCHF) approach, Cl V [10], Mn XIII [11], Co xv [12], Fe XIV, and Ni XVI [13] using CIV3, S IV [14] and Ar VI [15] using configurationinteraction (CI) expansions, P III-Mo XXX [16], Xe XXXXII [17], and Au LXVII [18] using the many-body perturbation theory (MBPT) approach, Ca VIII [19] using the R-matrix approximation, K VII [20] using the multiconfiguration Hartree-Dirac-Fock method (MCDHF) method, and Si II [21] using the relativistic quantum defect orbital (RQDO) method. Both experiment and theory have been used to investigate the fine structure for medium-to low-Z ions.…”