J. H. Wood

Relativistic calculation of the electronic structure of UF6

Using a one‐component relativistic theory we have obtained the self‐consistent (SCF) one‐electron levels of UF6 via the multiple scattering (MS) Xα method. The calculated ionization energies are found to be in good agreement with the photoionization spectrum. Our first electronic transition (dipole forbidden) energy at 3.34 eV agrees well with the onset of absorption and the experimentally assigned transition at 3.04 eV. An analysis of the spin–orbit parameters, calculated via perturbation theory, is given. It is found that the contributions from the 6p components are especially important. We conclude that the absorption spectrum can not be interpreted in terms of the spin–orbit splitting of the highest occupied MO (tlu). A comparison is made with other relativistic (and nonrelativistic) one‐electron calculations of UF6. This comparison yields reasonable agreement on the relativistic one‐electron structure of this molecule.

Self‐consistent field calculation of the electronic structure of the uranyl ion (UO2++)

Using the multiple‐scattering Xα method the electronic ground state (1Σ+g) of the UO++2 molecule has been calculated self‐consistently. The self‐consistent calculations were performed at three U–O bond distances [3.269, 4.269, and 5.269 (a.u.)]. The four highest occupied one‐electron levels (σg, σu, Πg, Πu) of the ground state, which have received so much attention in the past, change ordering with decreasing bond distance but are so close in energy that the ordering may be unimportant in determining the absorption spectra. We have also computed the electronic transition energies for the excitations 1Σ+g → 1,3Φg(σ1uφ1u), 1Σ+g → 1,3Δg(σ1uφ1u), 1Σ+g → 1,3Πu, 1,3Φu(π3gδ1u), 1Σ+g → 1,3Δg, 1,3Γg(π3uφ1u), and 1Σ+g → 1,3Φg, 1,3Πg(π3uφ1u). All of these excitation energies fall in the region of the experimental absorption spectrum.

Electronic structure of UF6

The SCF‐X α‐SW method is used to carry out an approximate Hartree‐Fock calculation on the electronic structure on UF6−. The charge density within the atomic spheres is analyzed into its angular momentum components and the first two excited electronic states are computed.

A note on SCF calculations of valence levels in heavy molecules

Using a one‐component relativistic theory we have recently developed, we illustrate some interesting features of self‐consistent field (SCF) relativistic one‐electron calculations. In particular, it is demonstrated that nonrelativistic calculations of valence levels in actinide atoms and in molecules containing actinide atoms in which only the core states are treated relativistically, do not agree with fully relativistic results. Also it is found that if only the heavy atom(s) of a molecule is treated relativistically one obtains excellent agreement with a fully relativistic calculation. Non‐SCF relativistic calculations (using self‐consistent nonrelativistic potentials) are shown to give results equivalent to those obtained from first order perturbation theory. The differences between effects due to the relativistic portions of the Hamiltonian (direct) and effects due to the SCF process (indirect) are given for both atoms and molecules. The three examples used are the uranium atom, the UF6, and UO22+ mol...

Experimental and calculated electronic structure of gaseous CrO2F2 and CrO2Cl2

The gas phase electronic absorption spectra of CrO2F2 and CrO2Cl2 have been measured in the visible, near ultraviolet regions. Interpretation has been made by comparison with a molecular orbital calculation for each molecule by the SCF‐Xα‐SW method. The calculated ground and excited states and observed electronic transitions correlate directly with those for the parent isoelectronic CrO2−4 and MnO−4 species.

Relativistic electronic structure of UO2++, UO2+, and UO2

We have calculated the one‐electron energy level structures of the isolated species UO2++, UO2+, and UO2 in their linear forms, using a self‐consistent relativistic multiple scattering model with Xα exchange. For UO2++, we have used the molecular orbitals of the ground state muffin‐tin potential to calculate the energies of a few of the many‐electron excited states; these afford a somewhat more fundamental basis for comparison with experiment than do the one‐electron energies, and their determination also sheds some light on the coupling scheme (ω–ω vs Λ–Σ) to be expected in these systems. These excited state energies agree well with the experimental absorption data. The calculated one‐electron excitation energies for UO2++ are in reasonable agreement with the observed onset of absorption. The behavior of the corresponding one‐electron binding energies as a function of U–O distance supports a different interpretation of the XPS than that given by Veal et al. Considering the three species at a common bond ...

Calculated and experimental electronic structure of gaseous MnO3F and MnO3Cl

The gas phase electronic absorption spectra of MnO3F and MnO3Cl have been measured in the visible and near ultraviolet regions. Interpretation has been made by comparison with a molecular calculation for each molecule by the SCF–Xα–SW method in terms of C3v symmetry. The calculated ground and excited states and observed electronic transitions correlate directly with those for the parent MnO−4 cluster. The lowest excited state, 1Ea, which correlated with the first 1T1 state of MnO−4, retains the characteristics of the parent state. The charge transfer originating from the halide atom is first observed in the 1Ec excited state in each molecule correlating with the second lowest 1T2 state in MnO−4.

Rydberg states in H2O

Ionization and excitation energies for the Rydberg states (3,1B 1, 3,1A 2, 3,1A 1 lying above the ground state 1A 1) of the water molecule have been calculated via the multiple‐scattering X a (MSX a) method. Both singlet and triplet states have been computed self‐consistently. The first ionization energy of the molecule was also computed. In general, the results are in good agreement with experiment, and a few levels were found that have not been observed. The results were also compared with Hunt and Goddards recent improved virtual orbital (IVO) calculation on H2O.

Multiple scattering treatment of the solvated electron in water

The multiple scattering method of molecular orbital computations has been used to investigate the structure of an (excess) electron in water. The complex considered is a molecular ion consisting of four water molecules, situated on the vertices of a tetrahedron, plus the extra electron; the complex is placed in a dielectric cavity. The calculated excitation energy of 1.77 eV is in good agreement with the experimental value (1.72 eV). The computed equilibrium radius of the complex is in reasonable agreement with previous calculations. Our determination of a second ’’2p’’ state (5e) lying near the b2 state indicates another mechanism for the asymmetric line broadening of the absorption spectrum. Our computed self−consistent field potentials and charge densities are presented as they can be compared with previous model calculations.