Relativistic line strengths have been computed for a large number of transitions using Dirac wave functions for the one-electron, hydrogen-like ions. As expected, the results indicate that relativistic effects are quite small for low stages of ionization. However, in general, they also remain small throughout a large portion of the isoelectronic sequence, becoming typically of the order of 10 percent in the vicinity of = 50, after which they grow quite rapidly. This suggests that for multielectron ions a basically nonrelativistic theory might well be adequate for light atom isoelectronic ions through as much as 30 or 40 stages of ionization.
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http://dx.doi.org/10.6028/jres.079A.023 | DOI Listing |
Phys Chem Chem Phys
January 2025
Univ Rennes, CNRS, IPR (Institut de Physique de Rennes) - UMR 6251, F-35000 Rennes, France.
An accurate potential energy model, explicitly designed for studying scattering and treating the spin-orbit and nonadiabatic couplings on an equal footing, is proposed for the S + Ar system. The model is based on the Effective Relativistic Coupling by Asymptotic Representation (ERCAR) approach, building the geometry dependence of the spin-orbit interaction a diabatisation scheme. The resulting full diabatic model is used in close-coupling calculations to compute inelastic scattering cross sections for de-excitation from the S(D) fine structure level into the P multiplet.
View Article and Find Full Text PDFPhys Chem Chem Phys
January 2025
Institute of Inorganic Chemistry, Slovak Academy of Sciences, Dúbravská cesta 9, SK-84536 Bratislava, Slovakia.
The solvent effect on the indirect J(M-P) spin-spin coupling constant in phosphine selenoether -substituted acenaphthene complexes LMCl is studied at the PP86 level of nonrelativistic and four-component relativistic density functional theory. Depending on the metal, the solvent effect can amount to as much as 50% or more of the total -value. This explains the previously found disagreement between the J(Hg-P) coupling in LHgCl, observed experimentally and calculated without considering solvent effects.
View Article and Find Full Text PDFJ Chem Theory Comput
January 2025
Department of Chemistry, Graduate School of Advanced Science and Engineering, Hiroshima University, 1-3-1 Kagamiyama, Higashi-Hiroshima City, Hiroshima 739-8526, Japan.
Exploring electronic states in actinide compounds is a critical aspect of nuclear science. However, considering relativistic effects and electron correlation in theoretical calculations poses a complex challenge. To tackle this, we developed the CASPT2/RASPT2 program along with the DIRAC program, enabling calculations of electron correlation methods using multiconfigurational perturbation theory with various relativistic Hamiltonians.
View Article and Find Full Text PDFPhys Chem Chem Phys
January 2025
Institute of Applied Analysis and Numerical Simulation, University of Stuttgart, Pfaffenwaldring 57, Stuttgart, 70569, Germany.
In this study, we report a comprehensive calculation of the static dipole polarizabilities of group 12 elements using the finite-field approach combined with the relativistic coupled-cluster method, including single, double, and perturbative triple excitations. Relativistic effects are systematically investigated, including scalar-relativistic, spin-orbit coupling (SOC), and fully relativistic Dirac-Coulomb contributions. The final recommended polarizability values are 37.
View Article and Find Full Text PDFSci Bull (Beijing)
January 2025
School of Physics and State Key Laboratory of Nuclear Physics and Technology, Peking University, Beijing 100871, China; Center for High Energy Physics, Peking University, Beijing 100871, China; Key Laboratory of Particle Acceleration Physics and Technology, Chinese Academy of Sciences, Beijing 100049, China. Electronic address:
Dark photons, as a minimal extension of the Standard Model through an additional Abelian gauge group, may propagate relativistically across the galaxy, originating from dark matter decay or annihilation, thereby contributing to a galactic dark photon background. The generation of dark photons typically favors certain polarization modes, which are dependent on the interactions between dark matter and dark photons. We introduce a framework in which a resonant cavity is utilized to detect and differentiate these polarizations, leveraging the daily variation in expected signals due to the anisotropic distribution of dark photons and the rotation of the Earth.
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