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

Étude théorique de la régiosélectivité de l'ouverture des esters glycidiques par les organométalliques

Afin de contribuer à l'interprétation de la régiosélectivité de l'ouverture par les organométalliques des époxydes fonctionnalisés, nous avons étudié théoriquement la structure géométrique, la répartition des charges et la localisation des orbitales moléculaires du glycidate de méthyle non substitué ou substitué par un méthyle en C3 (configuration trans ou cis) et des complexes correspondants avec le cation lithium. Les calculs de type ab initio ont été effectués au niveau SCF avec une base minimale puis des bases étendues. Des trois facteurs possibles — électrostatique, stérique et de symétrie — seul le facteur stérique semble pouvoir expliquer la régiosélectivité de l'ouverture de ces composés par les cuprates lithiens

Blue satellite bands of KRb molecule: Intermediate long-range states

Three distinct satellite bands at 730–736 nm and a single shoulder at 755.5 nm that we assigned to KRb heteronuclear molecule are found in absorption measurements of hot K + Rb vapor. The interpretation of these bands is discussed in terms of recent ab initio calculations of the relevant potential curves. Semiclassical spectral simulations were performed with ab initio potentials and approximate transition dipole moment functions showing a good agreement with observations. The probabilities of cold molecule photoassociative formation into the external well of the double minimum (5)0+ state and decay to the ground state are discussed, and relative yields of molecular formation were estimated by using quantum mechanical calculations