Shell Effects in the Relaxation Energy of 2s‐Core Ionization of Atoms from B through Xe

Abstract

In this paper we investigate the variation, along the periodic table, of 2s-core ionization energies, using both relativistic and non-relativistic calculations. We show that electron relaxation energies display variations typical of the shellfilling process, while their relativistic contributions show specifically distorted shell features. Just as for the 1s-core ionization energies, investigated earlier, the sensitivity of these differential properties to the shell-filling process may be used as a probe of the accuracy of calculations of core ionization energies. Discrepancies with experimental results are critically analyzed.

Ansatz for the evaluation of the relativistic contributions to core ionization energies in complex molecules involving heavy atoms

“…3 for the split level energies: Therefore, for 2p levels we have four parameters (instead of two) to be optimized. The choice of fitting ΔE 1/2 and ΔE 3/2 rather than E and Δ 13 to allometric functions of E R ( n‐rt ) will be discussed in a further investigation involving all elements from Na through Xe 26. In this coming paper we will also investigate shell effects on the correlation energy within the 2p multiplet.…”

Electron cross relaxation as a function of single relaxation contributions in double‐core ionization energies and spin–orbit splitting of atoms from Ar to Ba. I. 1s−2p− double‐core holes

“…For elements from Ar to Ba (excluding transition elements), we have computed the nonrelaxed and relaxed core ionization energies for the single 1s, 2p 1/2 , and 2p 3/2 and double 1s‐2p 1/2 and 1s‐2p 3/2 ionizations, using procedures similar to those used in earlier papers 14–17.…”

“…Steps 1 and 2 were fulfilled by using, as in previous papers 14–17, Bruneau's multiconfiguration Breit–Dirac–Fock (MCBDF) ab initio program 31–33, which is based on a numerical resolution of the Dirac equation corrected for the Breit terms, vacuum polarization and radiative ( qed ) contributions, and nuclear size and motion ( nuc ) effects. Once the iterative resolution of the Dirac–Fock equations is performed (step mcdf ), the program provides the total energies for all J states and, for each atomic orbital nlj , the energy contribution, the effective Z *, and the average values < r >, < r 2 >, and <1/ r >.…”

“…In previous papers 14–17 we have investigated the relaxation and relativity effects in the 1s 14, 16, 2s 15, 16 and 2p 16, 17 core ionization energies of neutral atoms in the series LiXe, BXe, and ClBa. Owing to shell effects 18, 19, the variations of the energy contributions with atomic number Z are not monotonous but involve an irregular oscillating part.…”

“…In earlier work 27 we have tried to relate two satellites observed in the XPS near‐edge spectrum of SF 6 to (1s, 2p) “singlet” and “triplet” double‐core excitations, using a procedure of progressive corrections to simpler computations that was to be developed in later papers 14–17. The contribution of “cross relaxation,” due to the simultaneous occurrence of two core holes, played an important role in the methodology that we used.…”