Relativistic and QED corrections for the ground state lithiumlike ionization energies

The ground state ionization energies of Z ≤ 10 lithiumlike ions are calculated using fully correlated Gaussian wavefunctions. Leading-order relativistic corrections are evaluated, while QED corrections are established with small uncertainties by directly calculating the Araki-Sucher energy and expanding the three-electron Bethe logarithm in 1/Z. The non-relativistic α6 level shifts have also been calculated, and we have used these energies to recommend ionization energies, which include estimates of the influence of the relativistic portion of the α6 energy. The results emphasize the importance of the direct computation of the complete α6 correction, but also the need for new, higher accuracy experimental ionization limits.

The atomic structure of chemical elements in the theory of compressible oscillating ether

Previously, the basic laws and equations of electrodynamics, atomic nuclei, elementary particles theory and gravitation theory were derived from the equations of compressible oscillating ether. In this work, the theory of atomic structure for all chemical elements is constructed. A formula for the values of the energy levels of the electrons of an atom, which are the values of the energies of binding of electrons with the nucleus of an atom in the ground unexcited state, is derived from the equations of the ether. Based on experimental data on the ionization energies of atoms and ions, it is shown that the sequence of values of the energy levels of electrons has jumps, exactly corresponding to the periods of the table of chemical elements. It is concluded that it is precisely these jumps, and not quantum-mechanical rules, prohibitions and postulates that determine the periodicity of the properties of chemical elements. Ethereal correction of the table of chemical elements is presented which returns it to the form proposed by D.I. Mendeleev.

Calculation of Metallocene Ionization Potentials via Auxiliary Field Quantum Monte Carlo: Towards Benchmark Quantum Chemistry for Transition Metals

The accurate ab initio prediction of ionization energies is essential to understanding the electrochemistry of transition metal complexes in both materials science and biological applications. However, such predictions have been complicated by the scarcity of gas-phase experimental data, the relatively large size of the relevant molecules, and the presence of strong electron correlation effects. In this work, we apply all-electron phase-less auxiliary-field quantum Monte Carlo (ph-AFQMC) utilizing multi-determinant trial wavefunctions to six metallocene complexes to compare the computed adiabaticand vertical ionization energies to experimental results. We find the ph-AFQMC mean averaged errors (MAE) of 1.69±1.02 kcal/mol for the adiabatic energies and 2.85±1.13 kcal/mol for the vertical energies. This significantly outperforms density functional theory (DFT), which has MAE’s of 3.62 to 6.98 and 3.31 to 9.88 kcal/mol, as well as a localized coupled cluster approach (DLPNO-CCSD(T0) with moderate PNO cut-offs), which has MAEs of 4.96 and 6.08 kcal/mol, respectively. We also test the reliability of DLPNO-CCSD(T0) and DFT on acetylacetonate (acac) complexes for adiabatic energies measured in the same manner experimentally, and find higher MAE’s, ranging from 4.56 kcal/mol to 10.99 kcal/mol (with a different ordering) for DFT and 6.97 kcal/mol for DLPNO-CCSD(T0), indicating that none of these approaches can be considered benchmark methods, at least for these complexes. We thus demonstrate that ph-AFQMC should be able to handle metallocene redox chemistry with the advantage of systematically improvable results. By utilizing experimental solvation energies, we show that accurate reduction potentials in solution can be obtained.

Vacuum ultraviolet photoionization and dissociative photoionization of toluene: Experimental and theoretical insights

The photoionization and dissociative photoionization of toluene have been studied using synchrotron radiation vacuum ultraviolet light with photon energy in the range of 8.50–25.50 eV. The ionization energies (8.82 eV) and double ionization energies (23.80 eV) of toluene as well as the appearance energies for its major fragments C7H7+ (11.17/10.71 eV), C6H5+ (13.73 eV), C5H6+ (13.58/12.50 eV), C5H5+ (16.23 eV), C4H5+ (15.64 eV), C4H4+ (16.10 eV) and C4H3+ (17.11 eV) are determined, respectively by using photoionization efficiency spectrometry. With the help of experimental and theoretical results, seven dissociative photoionization channels have been proposed: C7H7+ + H, C6H5+ + CH3, C5H6+ + C2H2, C5H5+ + C2H2 + H, C4H5+ + C3H3, C4H4+ + C3H4 and C4H3+ + C3H4 + H. In addition, the geometries of the intermediates, transition states and products involved in these photoionization and dissociative photoionization processes have been performed at the B3LYP/6-311++G(d, p) level. The mechanisms of dissociative photoionization of toluene and the intermediates and transition states involved are discussed in detail. Generally speaking, the experimental results are in agreement with theoretical calculations in this work and published literature results. Especially the mechanisms of dissociative photoionization to C4H5+, C4H4+ and C4H3+ were discussed for the first time in this work. This investigation may provide useful information on understanding the photoionization and dissociative photoionization of toluene.

Hyperfine structure S state of muonic helium atom

In this work the nonrelativistic ionization energies 3He2+μ−e− and 4He2+μ−e− of helium-muonic atoms are calculated for S states.The estimates are based on the variational principle of exponential expansion. Convergence of the numerical values of variational energies is studied by increasing a number of the basis functions N. That allows to claim that the obtained energy values have 30-33 significant digits for S states

The Ionization Energies of Dust-Forming Metal Oxide Clusters

Stellar dust grains are predominantly composed of mineralic, anorganic material forming in the circumstellar envelopes of oxygen-rich AGB stars. However, the initial stage of the dust synthesis, or its nucleation, is not well understood. In particular, the chemical nature of the nucleating species, represented by molecular clusters, is uncertain. We investigated the vertical and adiabatic ionization energies of four different metal-oxide clusters by means of density functional theory. They included clusters of magnesia (MgO)n, silicon monoxide (SiO)n, alumina (Al2O3)n, and titania (TiO2)n with stoichiometric sizes of n = 1–8. The magnesia, alumina, and titania clusters showed relatively little variation in their ionization energies with respect to the cluster size n: 7.1–8.2 eV for (MgO)n, from 8.9–10.0 eV for (Al2O3)n, and 9.3–10.5 eV for (TiO2)n. In contrast, the (SiO)n ionization energies decrease with size n, starting from 11.5 eV for n = 1, and decreasing to 6.6 eV for n = 8. Therefore, we set constraints on the stability limit for neutral metal-oxide clusters to persist ionization through radiation or high temperatures and for the nucleation to proceed via neutral–neutral reactions.