Relativistic correlation effects on the hyperfine structure and electric dipole transitions in Cs and Tl

Abstract

A discrete numerical basis set is a versatile tool for many-body calculations. Here it is used to calculate second-order energy corrections and to construct approximate Brueckner orbitals for Cs and T1 in a relativistic framework. These orbitals, which often account for a large part of the correlation effects, are then used to evaluate the hyperfine structure and electric dipole transition matrix elements for a few low-lying states. The correlation effects were combined with the RPA diagrams, which account for the response of the orbitals to the external perturbation, and the results are compared with other calculations and with experiment. For Cs, the results are in good agreement with earlier work, whereas for the more complicated system T1 we find significantly larger contributions from the modification of the valence orbitals to approximate Brueckner orbitals.

Parity non-conservation and electric dipole moments in caesium and thallium

“…However, the results by Johnson et a1 (1988) showed a disagreement with the earlier calculation by Dzuba et a1 (1987a, b). Part of the discrepancy could be explained by the shielding effect on these contributions of the type shown in figure 2 (1988) and in our recent work (Hartley and MBrtensson-Pendrill 1990).…”

“…To estimate the error in the calculated PNC electric dipole transition matrix element, we turn again to the parity conserving properties calculated in earlier work (Hartley and MBrtensson-Pendrill 1990). For the hyperfine structure and electric dipole matrix elements discrepancies around 10% were found-except for the 6~312 hyperfine structure where large cancellations occur and even the sign is wrong.…”

Hyperfine structure in the 4d states of Rb-like Sr

“…Partly, this can be accounted for by using 'core polarization' potentials, which may explain the frequent success of semi-empirical approaches. Combining a lowest order evaluation of the Brueckner orbital corrections with the 'RPA' calculation gives agreement within 3% for the Cs hfs [12]. Additional correlation effects are usually much smaller for alkalis, but have to be accounted for in accurate calculations.…”

Excitation energies, hyperfine constants,E1,E2, andM1transition rates, and lifetimes ofSafronova1, Safronova2, Johnson3 2005Phys. Rev. A535520View full textAdd to dashboardCite

“…The ground-state energy of thallium, treated as a one-electron system, was calculated by Dzuba et al [1] using perturbation theory in a screened Coulomb interaction (PTSCI), by Blundell et al [2] using third-order many-body perturbation theory (MBPT), and by Liu and Kelly [3] using the coupled-cluster (CC) approach. Second-order MBPT energies of thallium were evaluated for the ground and excited states (6p 1/2 , 6p 3/2 , 7s 1/2 , and 7p 1/2 ) in Hartley and Martensson-Pendrill [4], where hyperfine constants for the four states listed above and electric-dipole transition matrix elements 7s − 6p 1/2 , 7s − 7p 1/2 , and 7s − 6p 3/2 were also evaluated. In all of the above calculations the three-electron state 6s 2 nl with 78 core electrons was considered as a one-electron nl system with an 80 electron core [Hg].…”