Insights into the structure and dynamics of liquid water: A comparative study of conventional QM/MM and ONIOM-XS MD simulations

► QM/MM and ONIOM-XS MD simulations of liquid water have been performed. ► The arrangement of hydrogen bonds in liquid water is found to be rather flexible. ► Large fluctuations in the number of hydrogen bonds were found, ranging from 2 to 6, with the prevalent value of 4. ► Numerous water exchange mechanisms were observed, with either “short-live” or “long-live” exchange periods.