Thermodynamic parameters of water calculated from its infrared OH stretching spectrum

Abstract

Excess thermodynamic parameters of H₂O water, corresponding to the difference between parameters for liquid water and ice, have been determined from the infrared O─H stretching spectra of very dilute solutions of HOD in D₂O. The analytical method applied considers the H-bonded O─H oscillators as a statistical ensemble. Comparison of the results with reference calorimetric data for water showed good correspondence for the excess free energy, enthalpy and entropy of water. There is a discrepancy between our calculation and calorimetric data for the specific heat capacity of supercooled water. It is attributed to the inadequacy of the vibrationally decoupled spectra to describe collective structures in water and their dynamic fluctuations.