  We propose a new approach to calculate van der Waals forces between
nanoparticles where the van der Waals energy can be reduced to the energy of
elementary surface plasmon oscillations in nanoparticles. The general theory is
applied to describe the interaction between 2 metallic nanoparticles and
between a nanoparticle and a perfectly conducting plane. Our results could be
used to prove experimentally the existence of plasmonic molecules and to
elaborate new control mechanisms for the adherence of nanoparticles between
each other or onto surfaces.
