Molecular dynamics study of water clusters, liquid, and liquid{endash}vapor interface of water with many-body potentials
- Environmental Molecular Sciences Laboratory, Pacific Northwest National Laboratory, Richland, Washington 99352 (United States)
The molecular dynamics computer simulation technique is used to develop a rigid, four-site polarizable model for water. The model reasonably describes the important properties of water clusters, the thermodynamic and structural properties of the liquid and the liquid/vapor interface of water. The minimum energy configurations and the binding energies for these clusters are in reasonable agreement with accurate electronic structure calculations. The model predicts that the water trimer, tetramer, and pentamer have cyclic planar minimum energy structures. A prismlike structure is predicted to be lowest in energy for the water hexamer, and a cagelike structure is the second lowest in energy, with an energy of about 0.2 kcal/mol higher than the prismlike structure. The results are consistent with recent quantum Monte Carlo simulations as well as electronic structure calculations. The computed thermodynamic properties for the model, at room temperature, including the liquid density, the enthalpy of vaporization, as well as the diffusion coefficient, are in excellent agreement with experimental values. Structural properties of liquid water, such as the radial distribution functions, neutron, and x-ray scattering intensities, were calculated and evaluated against the experimental measurements. We found the agreement between the observed data and the computed properties to be quite reasonable. The computed density profile of the water`s liquid/vapor interface shows that the interface is not sharp at a microscopic level and has a thickness of 3.2 {Angstrom} at 298 K. These results are consistent with those reported in earlier work. The calculated surface tension at room temperature is in reasonable agreement with experimental data. The computed average dipole moments of water molecules near the interface are close to their gas phase values, while water molecules far from the interface have dipole moments corresponding to their bulk values. (Abstract Truncated)
- Research Organization:
- Pacific Northwest National Lab. (PNNL), Richland, WA (United States)
- DOE Contract Number:
- AC06-76RL01830
- OSTI ID:
- 565272
- Journal Information:
- Journal of Chemical Physics, Vol. 106, Issue 19; Other Information: PBD: May 1997
- Country of Publication:
- United States
- Language:
- English
Similar Records
Many-body interactions in liquid methanol and its liquid/vapor interface: A molecular dynamics study
Liquid-Vapor Interface of Methanol-Water Mixtures: A Molecular Dynamics Study