Pentagon-pentagon correlations in water Abstract: We report computer simulation studies on the concentration of pentagon rins of hydrogen-bonded water molecules (pentagons) and on the spatial correlation of pentagons in liquid water. The pentagon-pentagon correlation function g₅₅(r) has a peak at r ~ 3.2 Å. The result supports the idea that the anomalies of water may be related to the self-replicating propensity of pentagons in the random network.