Return the communicability centrality for each node of G
Communicability centrality, also called subgraph centrality, of a node is the sum of closed walks of all lengths starting and ending at node .
Parameters :  G: graph : 

Returns :  nodes:dictionary :

Raises :  NetworkXError :

See also
Notes
This version of the algorithm exponentiates the adjacency matrix. The communicability centrality of a node in G can be found using the matrix exponential of the adjacency matrix of G [R138] [R139],
References
[R138]  (1, 2) Ernesto Estrada, Juan A. RodriguezVelazquez, “Subgraph centrality in complex networks”, Physical Review E 71, 056103 (2005). http://arxiv.org/abs/condmat/0504730 
[R139]  (1, 2) Ernesto Estrada, Naomichi Hatano, “Communicability in complex networks”, Phys. Rev. E 77, 036111 (2008). http://arxiv.org/abs/0707.0756 
Examples
>>> G = nx.Graph([(0,1),(1,2),(1,5),(5,4),(2,4),(2,3),(4,3),(3,6)])
>>> sc = nx.communicability_centrality_exp(G)