A Relativistic Equation-of-motion Coupled-Cluster Investigation of the Trends of Single and Double Ionization Potentials in the He and Be Isoelectronic Systems

摘要

We employ four-component spinor relativistic equation-of-motioncoupled-cluster (EOMCC) method within the single- and double- excitationapproximation to calculate the single ionization potentials (IPs) and doubleionization potentials (DIPs) of the He and Be isoelectronic sequences up to Ne.The obtained results are compared with the available results from the NationalInstitute of Standards and Technology (NIST) database to test the performanceof the EOMCC method. We also present intermediate results at different level ofapproximations in the EOMCC framework to gain insight of the effect of electroncorrelation. Furthermore, we investigate the dependence of the IPs and DIPs ofthese ions on the ionic charge and observe that these follow parabolic trends.Comparison between the trends of IPs and DIPs in both the classes of consideredsystems are categorically demonstrated.