Nucleation of a sodium droplet on C60

We investigate theoretically the progressive coating of C60 by several sodium atoms. Density functional calculations using a nonlocal functional are performed for NaC60 and Na2C60 in various configurations. These data are used to construct an empirical atomistic model in order to treat larger sizes in a statistical and dynamical context. Fluctuating charges are incorporated to account for charge transfer between sodium and carbon atoms. By performing systematic global optimization in the size range 1<=n<=30, we find that Na_nC60 is homogeneously coated at small sizes, and that a growing droplet is formed above n=>8. The separate effects of single ionization and thermalization are also considered, as well as the changes due to a strong external electric field. The present results are discussed in the light of various experimental data.Comment: 17 pages, 10 figure

MOCVD of rhenium-containing complex oxides with the new thd-precursor

Complex oxides containing rhenium, for instance, magnetoresistive double perovskites and Re-stabilised Hg high Tc superconductors, attract a significant attention. We developed a volatile rhenium compound compatible with the thd-complexes of metals by reaction of the product of the metal electrolysis with 2,2,6,6-tetramethylheptan-3,5-dion at the elevated temperature. The details of crystal structure of the compound are discussed. The blocks [ReO(thd)2](ReO4) form layered molecular structure. The compound was used in the single source MOCVD together with thd-complexes of different metals (Ba, La, Ho) producing films of the double oxides. The Restabilised Rex(Ba,Sr)2Ca2Cu3Oy (x=0.1-0.3) precursor films with high composition homogeneity and surface smoothness were deposited to be saturated with Hg under the high pressure

Crystal structure of copper(II) pivaloyltrifluoracetonate adducts with o-phenanthroline and 2,2'-dipyridyl

The crystal structure of Cu(pta)(2) . Phen has been determined. The phenanthroline ligand occupies a position in the equatorial plane of the tetragonally distorted octahedron with equal Cu-N distances and equivalent beta-diketonate-anions. Cu(pta)(2) . 2,2'-Dipy is isostructural to Cu(pta)(2) . Phen. The volatility of adducts decreases in the sequence Cu(thd)(2) . Phen, Cu(pta(2)). Phen and Cu(hfa)(2) . Phen changing inversely to that of the beta-diketonates. The variation of packing mode caused by the difference of the molecular structure is considered to be responsible for the effect. The changes of the electronic spectra of copper(II) beta-diketonates caused by adduct formation are discussed. (C) 1997 Elsevier Science Ltd