Ab initio Study of Interaction of Methanol with Water Molecule Clusters at Different Temperatures

Abstract

In this work, the interaction of one molecule of methanol with 9-16 molecules of water clusters in different temperatures (273.15- 453.15 K) has been studied. The intermolecular hydrogen bonding and DG and DH of formation of CH₃OH(H₂O)n (n = 9-16) clusters are calculated at the different temperatures. The calculations are performed at the DFT methods and B3LYP/6-31G* level of theory. It was shown that in all cases both the DH and DG of the formation of each cluster from the free molecules increase with increasing the number of water molecules in the cluster. The DH values of the formation of all clusters are negative in all temperatures but the corresponding DG values change to a positive number after a defined temperature, depending on the type and the size of the clusters.