A DFT study of temperature dependent dissociation mechanism of HF in HF(H2O)7 cluster

Abstract

We report a Density Functional Theoretical (DFT) study of dissociation of Hydrogen Fluoride (HF) in HF(H 2O) 7 cluster, using B3LYP functional and empirical exchange correlation functional M06-2X along with 6-31 + G(d,p) basis set. Dissociation constant, K RP, of HF dissociation and pK a values of HF in cluster at various temperatures have been reported. It has been found that both K RP and pK a are highly dependent on temperature. The variation of pK a with temperature suggests that HF is strong acid at lower temperatures. Our study also reveals that HF is a stronger acid in water cluster than in bulk water. Further, the results obtained by DFT calculations have been compared with the earlier reported results obtained from Monte Carlo (MC) simulation. It is found that DFT results are qualitatively consistent with the results of MC simulation but quantitatively different.