Accurate relativistic many-body calculations of van der Waals coefficients C_8 and C_10 for alkali-metal dimers

We consider long-range interactions between two alkali-metal atoms in their respective ground states. We extend the previous relativistic many-body calculations of C_6 dispersion coefficients [Phys.Rev. Lett. {\bf 82}, 3589 (1999)] to higher-multipole coefficients C_8 and C_10. A special attention is paid to usually omitted contribution of core-excited states. We calculate this contribution within relativistic random-phase approximation and demonstrate that for heavy atoms core excitations contribute as much as 10% to the dispersion coefficients. We tabulate results for both homonuclear and heteronuclear dimers and estimate theoretical uncertainties. The estimated uncertainties for C_8 coefficients range from 0.5% for Li_2 to 4% for Cs_2.Comment: 12 pages, submitted to Journal of Chemical Physic

Quantifying interactions on interfaces between metal partic¬les and oxide supports in catalytic nanomaterials

Metal-support interactions can dramatically affect the properties of nanocomposite materials. Nevertheless, comprehensive studies of the interfaces between metal nanoparticles and oxide supports remain scarce due to challenges in experimental characterization. A significant understanding of the interactions at such interfaces can be obtained by combining state-of-the-art experiments with density functional calculations. In particular, this Perspective illustrates how theory and experiment can be combined to study interfacial charge transfer, the short- or long-range natures of nanoparticle-support interactions and the effects of oxide nanostructuring on the properties of supported metal particles. These studies aid our understanding of the role of metal-oxide interactions in industrially employed nanocomposites and the design of interfaces with unique properties for future applications

Effects of electron transfer in model catalyst composed of Pt nanoparticles on CeO2(111) surface

Interactions between transition metal nanoparticles and reducible oxide supports are thought to significantly affect the performance of many catalysts. Usually, several metal-support effects act together and cannot be separated from each other. Herein, by means of density-functional calculations we succeeded to single out and quantify effects of the metal-support electron transfer on the structure and electronic properties of important model Pt-ceria catalysts. Namely, we considered ∼1.5 nm large Pt95 and Pt122 particles supported on CeO2(1 1 1). We show that Pt-ceria interactions notably reconstruct Pt nanofacets forming the interface and shift valence d-states of the Pt particles. These effects are rather insensitive to the Pt-ceria electron transfer, at variance with the electronic structure of oxygen anions at the interface, which is significantly affected by the electron transfer. The findings of this work and the special modeling approach applied pave the way for deeper analysis of electronic metal-support interactions in catalysis