Quantum effects on liquid dynamics as evidenced by the presence of well-defined collective excitations in liquid para-hydrogen

The origin of the well-defined collective excitations found in liquid para-H2 by recent experiments is investigated. The persistence of their relatively long lifetimes down to microscopic scales is well accounted for by calculations carried out by means of path-integral-centroid molecular dynamics. In contrast only overdamped excitations are found in calculations carried within the classical limit. The results provide fully quantitative evidence of quantum effects on the dynamics of a simple liquid.

On the Location of Li(+) Cations in the Fast Li-Cation Conductor La(0.5)Li(0.5)TiO(3) Perovskite.

Lithium cations sit in the center of the oxygen "windows" defined by the vertex-sharing TiO(6) octahedra of the title compound (see picture), as shown from neutron diffraction data. The octahedra are tilted to optimize the bond distances between the atoms. The unusual coordination and the partially unoccupied sublattice (occupancy factors 1/6 and (1/2) for Li and La, respectively) account for the high mobility of the Li(+) cations.