code: public static final void rotate(Group group, Matrix m){
  
  		AtomIterator iter = new AtomIterator(group) ;
  
  		while (iter.hasNext()) {
  			Atom atom = iter.next() ;
  			rotate(atom,m);
  
  		}
  
  	}
docs: Rotate a group object. The rotation Matrix must be a pre-multiplication
  Matrix.
  
  @param group
  a group to be rotated
  @param m
  a Matrix object representing the rotation matrix