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Surface potential of the water liquid-vapor interface
M A Wilson1, A Pohorille, L R Pratt
1Department of Chemistry, University of California, Berkeley 94720, USA.
The Journal of Chemical Physics
|March 1, 1988
Summary
Molecular dynamics simulations reveal the water liquid-vapor interface has a surface potential of -(130 +/- 50) mV. This value, while reasonable in magnitude, has the opposite sign compared to experimental expectations.
Area of Science:
- Physical Chemistry
- Computational Chemistry
- Surface Science
Background:
- The surface potential of the water liquid-vapor interface is crucial for understanding interfacial phenomena.
- Previous experimental studies suggest a small surface potential, typically 10-100 mV.
Purpose of the Study:
- To investigate the surface potential of the water liquid-vapor interface using molecular dynamics simulations.
- To reconcile discrepancies between theoretical predictions and experimental observations.
Main Methods:
- Molecular dynamics simulations employing the TIP4P water model.
- Analysis of electrostatic potential variation with depth into the liquid.
Main Results:
- The TIP4P model predicts a surface potential of -(130 +/- 50) mV, opposite in sign to experimental expectations.
- The electrostatic potential exhibits nonmonotonic variation due to H2O molecular orientation at the interface.
- Minor adjustments to molecular charge distribution can align computed values with experimental expectations.
Conclusions:
- The TIP4P model's prediction for surface potential requires refinement, particularly concerning molecular charge distribution.
- The surface environment may significantly alter electron distribution wings, impacting surface potential calculations.
- Further investigation into the electronic structure of water at interfaces is warranted.