Molecular Clusters
In chemistry, an atom cluster is an ensemble of bound atoms or molecules that is intermediate in size between a simple molecule and a nanoparticle; that is, up to a few nanometers in diameter. Clusters with a definite number and type of atoms in a specific arrangement are often considered a specific chemical compound and are studied as such. For example, fullerene is a cluster of 60 carbon atoms arranged as the vertices of a truncated icosahedron, and decaborane is a cluster of 10 boron atoms forming an incomplete icosahedron, surrounded by 14 hydrogen atoms. Water molecules can join by hydrogen bonds to form water clusters. The term is most commonly used for ensembles consisting of several atoms of the same element, or of a few different elements, bonded in a three-dimensional arrangement. Transition metals and main group elements form especially robust clusters.
