A study of H-bonded (HF)-n clusters within the framework of the electronic model

Properties of H-bonded linear (HF)n clusters are considered in terms of the electrostatic model. The expression for the potential energy of such clusters includes Coulomb interaction of effective (residual) atomic charges, the polarizing action of these charges on neighboring molecules, and the exchange repulsion between nearest neighbors. This model was used to calculate the energy of the formation of the dimer (HF)2 and the trimer (HF)3, v-s(HF) frequency shifts accompanying the formation of these clusters, and the dependence of the dopole moment and the intensity of the v-s(HF) vibration on the number of molecules in the (HF)n cluster. The results are in satisfactory agreement with the experiment and with ab initio calculation data. The contributions of cooperative (trimolecular) interaction to the energy of the trimer (-8 per cent) and the frequency shift and the intensity of the v-s(HF) mode (1-2 per cent) were determined. In the weak-field approximation, the dipole moment does not include cooperative effects.