Hydrogen-Bond Cooperative Effects in Small Cyclic Water Clusters as Revealed by the Interacting Quantum Atoms Approach

The cooperative effects of hydrogen bonding in small water clus- ters (H2O)n (n = 3-6) have been studied by using the partition of the electronic energy in accordance with the interact- ing quantum atoms (IQA) approach. The IQA energy splitting is comple- mented by a topological analysis of the electron density (1(r)) compliant with the quantum theory of atoms-in-mole- cules (QTAIM) and the calculation of electrostatic interactions by using one- and two-electron integrals, thereby avoiding convergence issues inherent to a multipolar expansion. The results show that the cooperative effects of hy- drogen bonding in small water clusters arise from a compromise between: 1) the deformation energ…