Understanding chemical coupling in cyclic versus compact water clusters with the Ehrenfest Force

We explain why differences in the nature of the chemical coupling in the compact (H2O)6 cluster and cyclic (H2O)4 cluster results in relatively stronger hydrogen-bonds in (H2O)4 compared with (H2O)6. We have investigated and visualized the nature of the two-way donation of both covalent and hydrogen-bond character between covalent (sigma) and hydrogen-bonds. This was undertaken by calculating the precessions K' of the eigenvectors around the bond-path for the Ehrenfest Force F(r) and compared with the corresponding QTAIM K'. We explain the success of the Ehrenfest Force F(r) in determining the chemical coupling underlying the unusual strength of hydrogen-bonds in water.

Automated summary

This study analyzes the differences in chemical coupling between (H2O)4 and (H2O)6, explaining the stronger hydrogen bonds in (H2O)4. By investigating the nature of two-way donation between covalent and hydrogen bonds and comparing different methods, the success of using Ehrenfest Force in determining the chemical coupling underlying the unusual strength of hydrogen bonds in water is demonstrated.