A STUDY OF H-BONDED (HF)(N) CLUSTERS WITHIN THE FRAMEWORK OF THE ELECTROSTATIC MODEL

Properties of H-bonded linear (HF)(n) clusters are considered in terms of the electrostatic model. The expression for the potential energy o f such clusters includes Coulomb interaction of effective (residual) a tomic charges, the polarizing action of these charges on neighboring m olecules, and the exchange repulsion between nearest neighbors. This m odel was used to calculate the energy of the formation of the dimer (H F)(2) and the trimer (HF)(3), nu(s)(HF) frequency shifts accompanying the formation of these clusters, and the dependence of the dipole mome nt and the intensity of the nu(s)(HF) vibration on the number of molec ules in the (HF)(n) cluster. The results are in satisfactory agreement with the experiment and with ab initio calculation data. The contribu tions of cooperative (trimolecular) interaction to the energy of the t rimer (similar to 8%) and the frequency shift and the intensity of the nu(s)(HF) mode (1-2%) were determined. In the weak-field approximatio n, the dipole moment does not include cooperative effects.