#	Filter for analyzing two-dimensional systems. For any number 
#	of edges n, the associated Voronoi cell topology is a the
#	prism over an n-gon.  For triagonal crystalline systems,
#	atoms whose Voronoi cells have six edges can be considered
#	crystalline, and those with more than or few can be considered
#	as belonging to defects. 
*	1	Three
*	2	Four
*       3       Five  
*       4       Six 
*       5       Seven
*	6	Eight
*	7	Nine
*	8	Ten
*	9	Eleven
*	10	Twelve
1	(1,2,3,1,3,4,5,1,5,6,2,6,4,6,5,4,3,2,1)
2       (1,2,3,4,1,4,5,6,1,6,7,2,7,8,3,8,5,8,7,6,5,4,3,2,1)     
3	(1,2,3,4,1,4,5,6,1,6,7,8,2,8,9,3,9,10,5,10,7,10,9,8,7,6,5,4,3,2,1)	
4	(1,2,3,4,1,4,5,6,1,6,7,8,9,2,9,10,3,10,11,12,5,12,7,12,11,8,11,10,9,8,7,6,5,4,3,2,1)    
5	(1,2,3,4,1,4,5,6,1,6,7,8,9,10,2,10,11,3,11,12,13,14,5,14,7,14,13,8,13,12,9,12,11,10,9,8,7,6,5,4,3,2,1)	
6	(1,2,3,4,1,4,5,6,1,6,7,8,9,10,11,2,11,12,3,12,13,14,15,16,5,16,7,16,15,8,15,14,9,14,13,10,13,12,11,10,9,8,7,6,5,4,3,2,1)	
7	(1,2,3,4,1,4,5,6,1,6,7,8,9,10,11,12,2,12,13,3,13,14,15,16,17,18,5,18,7,18,17,8,17,16,9,16,15,10,15,14,11,14,13,12,11,10,9,8,7,6,5,4,3,2,1)	
8	(1,2,3,4,1,4,5,6,1,6,7,8,9,10,11,12,13,2,13,14,3,14,15,16,17,18,19,20,5,20,7,20,19,8,19,18,9,18,17,10,17,16,11,16,15,12,15,14,13,12,11,10,9,8,7,6,5,4,3,2,1)	
9	(1,2,3,4,1,4,5,6,1,6,7,8,9,10,11,12,13,14,2,14,15,3,15,16,17,18,19,20,21,22,5,22,7,22,21,8,21,20,9,20,19,10,19,18,11,18,17,12,17,16,13,16,15,14,13,12,11,10,9,8,7,6,5,4,3,2,1)	
10	(1,2,3,4,1,4,5,6,1,6,7,8,9,10,11,12,13,14,15,2,15,16,3,16,17,18,19,20,21,22,23,24,5,24,7,24,23,8,23,22,9,22,21,10,21,20,11,20,19,12,19,18,13,18,17,14,17,16,15,14,13,12,11,10,9,8,7,6,5,4,3,2,1)