Structure and Partition Function of Liquid Water. III. Development of the Partition Function for a Band Model of Water

Abstract

A partition function for liquid water is developed, based on the three types of water molecules postulated by Buijs and Choppin. The main feature of this approach is that the concept of discrete energy levels (corresponding to zero, one, and two hydrogen bonds) is abandoned and replaced by the idea of energy bands. The parameters of the partition function are evaluated from the thermodynamic data at 50°C, the results of Buijs and Choppin, and the assumption of dipole—dipole forces within the liquid. These parameters are then used to calculate the thermodynamic functions over the range 0° to 100°C. The calculated results are in very good agreement with the experimental observations, the agreement with C_v being generally better than 0.2%. The experimental results of Buijs and Choppin and our band model of water are therefore consistent with each other and also with thermodynamic data on water.