Why do dipole moments of HCl–water clusters fail to determine acid dissociation?

Abstract

This paper quantitatively examines why dipole moments of HCl(H₂O)_n=1–8 cannot serve as the dissociation criterion for acid molecules using the Hirshfeld-I approach. Also, we propose the possible experimental parameter 〈P_(HCl)〉, whose statistical average enables the assessment of acid dissociation in mixed clusters. Furthermore, our calculations reveal that a minimum of four water molecules are necessary to dissociate an HCl molecule.