Vibrational Sum Frequency Generation Spectroscopy of the Water Liquid–Vapor Interface from Density Functional Theory-Based Molecular Dynamics Simulations
Résumé
The vibrational sum frequency generation (VSFG) spectrum of the water liquid-vapor (LV) interface is calculated using density functional theory-based molecular dynamics simulations. The real and imaginary parts of the spectrum are in good agreement with the experimental data, and we provide an assignment of the SFG bands according to the dipole orientation of the interfacial water molecules. We use an instantaneous definition of the surface, which is more adapted to the study of interfacial phenomena than the Gibbs dividing surface. By calculating the vibrational (infrared, Raman) properties for interfaces of varying thickness, we show that the bulk spectra signatures appear after a thin layer of 2-3 Å only. We therefore use this value as a criterion for calculating the VSFG spectrum.
Mots clés
Molecular dynamics simulations
Liquid-vapor interface
Liquid-vapor
Vibrational sum-frequency generations
Molecular dynamics
Thin layers
Bulk spectra
Density functionals
Dipole orientation
Dividing surfaces
Imaginary parts
Interfacial phenomena
Interfacial water molecules
Varying thickness
Density functional theory
Vapors