Relativistic and QED corrections to one-bond indirect nuclear spin-spin couplings in X2^{2+} and X3^{2+} ions (X = Zn, Cd, Hg)

COLOMBO JOFRÉ, MARIANO TOMÁS; KOZIOL, KAROL; AUCAR, IGNACIO AGUSTÍN; GAUL, KONSTANTIN; BERGER, ROBERT; AUCAR, GUSTAVO ADOLFO

Assisi

Conferencia; 13TH INTERNATIONAL CONFERENCE ON RELATIVISTIC EFFECTS IN HEAVY-ELEMENTS CHEMISTRY AND PHYSICS (REHE 2022); 2022

The indirect spin-spin coupling tensor, J, between mercury nuclei in systems containing this element can be of the order of few kHz and is one of the largest measured. We analysed the physics behind the electronic mechanisms that contribute to the one- and two-bond couplings ^nJ(Hg-Hg) (n=1, 2). For doing so, we performed calculations for J-couplings in the ionized X2^{2+} and X3^{2+} linear molecules (X = Zn, Cd, Hg) within polarization propagator theory, using the random phase approximation and the pure zeroth-order approximation with Dirac-Hartree-Fock and Dirac-Kohn-Sham orbitals, both at four-component and two-component levels. We show that the “paramagnetic-like” mechanism contribute with more than 99.98% to the total isotropic value of the coupling tensor. By analyzing the molecular and atomic orbitals involved in the total value of the response function, we find that the s-type valence atomic orbitals play a predominant role in the description of the coupling. This fact allows us to develop an effective model from which QED effects on J-couplings in the aforementioned ions can be estimated. Those effects were found to be within the interval (0.7; 1.7)% of the total relativistic effect on isotropic one-bond ^1J coupling, though ranging those corrections between the interval (-0.4; -0.2)% in Zn-containing ions, to (-1.2; -0.8)% in Hg-containing ions, of the total isotropic coupling constant in the studied systems. The estimated QED corrections show a visible dependence on the nuclear charge Z of each atom X in the form of a power-law proportional to Z_X^5.