In
chemistry, a
cluster is an ensemble of bound
atoms or
molecules that is intermediate in size between a
molecule and a bulk
solid. Clusters exist of diverse stoichiometries and nuclearities. For example,
carbon and
boron atoms form
fullerene and
borane clusters, respectively. Transition metals and main group elements form especially robust clusters. Clusters can also consist solely of a certain kind of molecules, such as
water clusters.