  The conducting and thermodynamic properties of ballistic metallic
nanocontacts with smooth shapes are investigated. All properties are related to
the electronic scattering matrix, which is evaluated in the WKB approximation
for independent electrons and in the self-consistent Hartree approximation for
interacting electrons. Mesoscopic oscillations of order 1nN in the cohesive
force and of order e in the contact charge are predicted when a metallic
nanocontact is pulled apart, which are synchronized with quantized jumps in the
conductance.
