Significant-Structure Theory Applied to Water and Heavy Water

Abstract

Significant-structure theory has been successfully applied to water and heavy water. The thermodynamic and transport properties have been calculated and the theory gives maximum density at near 4°C for H2O and at near 11.23°C for D2O. Further, the calculated results for entropy of vaporization, vapor pressure, molar volume, heat capacity, and the critical values are in good agreement with the observed values. The calculated curve for viscosity under pressure above 1 atm shows the observed minimum and is in satisfactory numerical agreement with the experimental values. According to our model, clusters of Ice-I-like molecules are in equilibrium with Ice-III-like molecules. The lifetime of the Ice-I-like cage structures is long compared to the relaxation time in viscous flow but fast compared to the relaxations observed in NMR.