Density-functional computation of (99)Tc NMR chemical shifts.

99Tc chemical shifts of TcO4(-), TcH9(2-), TcOF5, TcO2F4(-), TcOCl4(-), Tc2(CO)10, and Tc(CO)3L3(+) (L = CO, MeCN, H2O) are computed using geometries optimized with the gradient-corrected BP86 and hybrid B3P86 density functionals, at the gauge-including atomic orbitals (GIAO), -BPW91 and -B3LYP levels. For this set of compounds, substituent effects on delta(99Tc) are better described with the pure BPW91 functional than with B3LYP, in contrast to most other transition-metal chemical shifts studied so far. A rough, qualitative correlation is found between computed electric-field gradients at the Tc nuclei and the corresponding 99Tc NMR line widths.

Density functional theory study of uranium(VI) aquo chloro complexes in aqueous solution.

Mixed uranyl aquo chloro complexes of the type [UO2(H2O)xCly]2-y (y = 1, 2, 3, 4; x + y = 4, 5) have been optimized at the BLYP, BP86, and B3LYP levels of density functional theory in vacuo and in a polarizable continuum modeling bulk water (PCM) and have been studied at the BLYP level with Car-Parrinello molecular dynamics (MD) simulations in the gas phase and in explicit aqueous solution. Free binding energies were evaluated from static PCM data and from pointwise thermodynamic integration involving constrained MD simulations in water. The computations reveal significant solvent effects on geometric and energetic parameters.

Binding of pertechnetate to uranyl(VI) in aqueous solution. A density functional theory molecular dynamics study.

According to constrained Car-Parrinello molecular dynamics simulations and thermodynamic integration, the free binding energy between uranyl hydrate and pertechnetate in aqueous solution is significantly lower than that between uranyl and nitrate, namely, by 1.7 kcal mol(-1). This is the first study of the differential binding of these two ligands to uranyl, which can have implications for the separability of uranium and technetium during the reprocessing of nuclear waste.

Structural properties of screened Coulomb balls.

Small three-dimensional strongly coupled charged particles in a spherical confinement potential arrange themselves in a nested shell structure. By means of experiments, computer simulations, and theoretical analysis, the sensitivity of their structural properties to the type of interparticle forces is explored. While the normalized shell radii are found to be independent of shielding, the shell occupation numbers are sensitive to screening and are quantitatively explained by an isotropic Yukawa model.

Temperature-dependent quantum pair potentials and their application to dense partially ionized hydrogen plasmas.

Extending our previous work [J. Phys. A 36, 5957 (2003)]], we present a detailed discussion of accuracy and practical applications of finite-temperature pseudopotentials for two-component Coulomb systems.