In contrast, H2O in ice is abnormal . A breakpoint is found at M.P. due to the abrupt decrease of density, and A=9.2823 corresponds to n≥19 below M.P. It is hard to get so many symmetry operations from H2O in gas. Meanwhile, such a large A (>9) is only found in the longer alkanes (C > 4) near M.P. Moreover, it is rare even in alcohols, i.e., methanol, ethanol, propanol, and isopropanol. Therefore, two causes are possible. The first is that migrating two hydrogen atoms among the four vertices of an O sp 3 tetrahedron increases the operation number. The second is that the complex forms due to the strong H-bonds at the temperature below M. P.