How intermolecular charge transfer influences the air-water interface.

The interfacial properties of three water models that allow for intermolecular charge rearrangement were examined with molecular dynamics simulations. They included the TIP4P water model, the TIP4P-FQ water model, which recently were modified to include intermolecular charge transfer [A. J. Lee and S. W. Rick, J. Chem. Phys. 134, 184507 (2011)]. Furthermore, another model with intermolecular charge transfer was developed for this work that was both flexible and polarizable. The effect of including intermolecular charge transfer is modest on most interfacial properties, including surface tension, electrostatic potential, interfacial dipole, and structure. However, a negative charge was found to build up at the air-water interface, but much smaller than has been measured experimentally.