code: public static final Atom[] centerAtoms(Atom[] atomSet)
  			throws StructureException {
  
  		Atom centroid = getCentroid(atomSet);
  		return centerAtoms(atomSet, centroid);
  	}
docs: Center the atoms at the Centroid.
  
  @param atomSet
  a set of Atoms
  @return an Atom representing the Centroid of the set of atoms
  @throws StructureException