How flexible is the water molecule geometry? Analysis of crystal structures and potential energy surface.

Water molecules from crystal structures archived in CSD show relatively large range both in the bond angle and bond lengths. High level ab-initio calculations at CCSD(T) level predicted a possibility for energetically low-cost (± 1 kcal/mol) change of the bond angle and bond lengths in wide range, from 96.4⁰ to 112.8⁰ and from 0.930 A to 0.989 A, respectively.