Articles you may be interested inTime-dependent four-component relativistic density-functional theory for excitation energies. II. The exchangecorrelation kernel J. Chem. Phys. 123, 054102 (2005); 10.1063/1.1940609 Scalar relativistic all-electron density functional calculations on periodic systems J. Chem. Phys. 122, 084108 (2005); 10.1063/1.1851973 Response to "Comment on 'Four-component relativistic density functional calculations of heavy diatomic molecules'" [Comment on "Four-component relativistic density functional calculations of heavy diatomic molecules" [J. Chem.Molecular density functional calculations in the regular relativistic approximation: Method, application to coinage metal diatomics, hydrides, fluorides and chlorides, and comparison with first-order relativistic calculationsWe perform accurate four-component calculations for heavy closed-shell diatomic molecules in the framework of relativistic density functional theory using local and gradient corrected density functional schemes. As examples we have chosen Cu 2 , Ag 2 , Au 2 , Tl 2 , Pb 2 , Bi 2 , and Pt 2 . The potential energy curves show the quality, and the discrepancies of the density functionals unscreened from any approximation of the relativistic effects.

were studied by the total electron yield method. Peaks were observed at 59.9, 60.3 and 61.4 eV in the XANES spectra of Li 3 PO 4 , Li 2 SO 4 ·H 2 O and LiNO 3 , respectively. The peak of the each sample was assigned as the core exciton. In the XANES spectra of Li 2 O, Li 2 S, Li metal, LiOH·H 2 O and Li 2 CO 3 , there were shoulder structures at the same energy. To clarify the origin of each peak, the XANES spectra were examined with the discrete variational (DV)-Xa molecular orbital method. Comparing the measured spectra with the calculated wavefunction, the shoulder structures at 61.8 eV (Li 2 O) and 60.4 eV (Li 2 S) in the XANES spectra were assigned as the core excitons, which appeared as remarkable exciton peaks in the lithium halide spectra. The spectrum of each lithium compound could be classified according to the shape of the core exciton peak, namely either a sharp or a shoulder structure. The strength of the ionic bond determined which of these shapes a core exciton peak assumed.

We have studied the relativistic effects in the electronic structure and chemical bonding for the ground state of UF6, using the relativistic and nonrelativistic discrete-variational Xα molecular orbital calculations. It is found that two relativistic effects appear in the valence levels; the energy level splitting and upward shift of energies of the molecular orbitals. From the Mulliken population analysis of the valence levels, it is shown that the level splitting is due to mixing of the uranium atomic orbitals with a strong spin–orbit interaction, such as U6p, and the upward shift due to the increase in the screening of the nuclear charge and charge redistribution. The strength of U–F bonding remarkably increases for the relativistic case, because the changes in the radial distributions due to the relativistic effects induce both the decrease in the antibonding interactions and the increase in the bonding ones.

We have performed molecular orbital calculations for SF 6 and H2 S, using the discretevariational Xa method. Energies and cross sections of virtual states are obtained for theoretical spectra of sulfur K, L n . lIl and fluorine K x-ray absorptions for the SF 6 molecule. They are in good agreement with the experimental results. Through the same calculation procedures, the theoretical spectra of sulfur K and L n . lIl absorptions for H2 S are derived. The obtained molecular orbitals represent the experimental spectra below the ionization energy very well. SF 6 has distinct shape resonances above the ionization energy, in contrast to HzS which has pre-edge peaks as a main structure. For the SF 6 molecule, shape resonances come from the scattering at the steep change of attractive potential of surrounding fluorine atoms. It is demonstrated that phase shift due to the scattering causes the resonances without a potential barrier. Various spectral differences among the sulfur K, L n . lIl and the fluorine K absorptions in peak width and in base line are related to the character of wave functions. Other resonances among the fluorine wave functions contribute to the characteristics of the base line which was explained as the continuum state alone previously. For the H 2 S molecule, the reason for the absence of resonances is attributable to the weak scattering power of hydrogen atoms.