The changes in the mean-square charge radius (relative to 209Bi), magnetic dipole, and electric quadrupole moments of 187, 188, 189, 191Bi were measured using the in-source resonance-ionization ...spectroscopy technique at ISOLDE (CERN). A large staggering in radii was found in 187, 188, 189Big, manifested by a sharp radius increase for the ground state of 188Bi relative to the neighboring 187, 189Big. A large isomer shift was also observed for 188Bim. Both effects happen at the same neutron number, N = 105 , where the shape staggering and a similar isomer shift were observed in the mercury isotopes. Experimental results are reproduced by mean-field calculations where the ground or isomeric states were identified by the blocked quasiparticle configuration compatible with the observed spin, parity, and magnetic moment.
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The tiny-core generalised (Gatchina) relativistic pseudopotential (GRPP) model provides an accurate approximation for many-electron Hamiltonians of molecules containing heavy atoms, ensuring a proper ...description of the effects of non-Coulombian electron-electron interactions, electronic self-energy and vacuum polarisation. Combining this model with electron correlation treatment in the frames of the intermediate Hamiltonian Fock space coupled cluster theory employing incomplete main model spaces, one obtains a reliable and economical tool for excited state modelling. The performance of this method is assessed in applications to ab initio modelling of excited electronic states of the thorium monoxide molecule with term energies below 20,000 cm
. Radiative lifetimes of excited states are estimated using truncated expansions of effective and metric operators in powers of cluster amplitudes.
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4.
Electron affinity of oganesson Kaygorodov, M. Y.; Skripnikov, L. V.; Tupitsyn, I. I. ...
Physical review. A,
07/2021, Volume:
104, Issue:
1
Journal Article
Peer reviewed
Open access
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Ab initio study and assignment of electronic states in molecular RaCl Isaev, T.A.; Zaitsevskii, A.V.; Oleynichenko, A. ...
Journal of Quantitative Spectroscopy & Radiative Transfer/Journal of quantitative spectroscopy & radiative transfer,
July 2021, 2021-07-00, 2021-07-01, Volume:
269, Issue:
C
Journal Article
Peer reviewed
Open access
•Electronic structure of RaCl is studied with relativistic Fock-space coupled cluster method.•Based on the computed level energies, a reassignment of previously reported levels is proposed.•We found ...a favourable situation for laser cooling of RaCl, according to computed potential energy surfaces for the energetically lowest electronic states.•A number of molecular P-odd and P, T-odd properties in the framework of a quasirelativistic zeroth-order regular approach is calculated.
Radium compounds have attracted recently considerable attention due to both development of experimental techniques for high-precision laser spectroscopy of molecules with short-lived nuclei and amenability of certain radium compounds for direct cooling with lasers. Currently, radium monofluoride (RaF) is one of the most studied molecules among the radium compounds, both theoretically and recently also experimentally. Complementary studies of further diatomic radium derivatives are highly desired to assess the influence of chemical substitution on diverse molecular parameters, especially on those connected with laser cooling, such as vibronic transition probabilities, and those related to violations of fundamental symmetries. In this article high-precision ab initio studies of electronic and vibronic levels of diatomic radium monochloride (RaCl) are presented. Recently developed approaches for treating electronic correlation with Fock-space coupled cluster methods are applied for this purpose. Theoretical results are compared to an early experimental investigation by Lagerqvist and used to partially reassign the experimentally observed transitions and molecular electronic levels of RaCl. Effective constants of P-odd hyperfine interaction Wa and P,T-odd scalar-pseudoscalar nucleus-electron interaction Ws in the ground electronic state of RaCl are estimated within the framework of a quasirelativistic Zeroth-Order Regular Approximation approach and compared to parameters in RaF and RaOH.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
The Fock space relativistic coupled cluster method (FS-RCC) is one of the most promising tools of electronic structure modeling for atomic and molecular systems containing heavy nuclei. Until ...recently, capabilities of the FS-RCC method were severely restricted by the fact that only single and double excitations in the exponential parametrization of the wave operator were considered. We report the design and the first computer implementation of FS-RCC schemes with full and simplified non-perturbative account for triple excitations in the cluster operator. Numerical stability of the new computational scheme and thus its applicability to a wide variety of molecular electronic states is ensured using the dynamic shift technique combined with the extrapolation to zero-shift limit. Pilot applications to atomic (Tl, Pb) and molecular (TlH) systems reported in the paper indicate that the breakthrough in accuracy and predictive power of the electronic structure calculations for heavy-element compounds can be achieved. Moreover, the described approach can provide a firm basis for high-precision modeling of heavy molecular systems with several open shells, including actinide compounds.
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