Structure of the Methanol Liquid−Vapor Interface: A Comprehensive Particle-Based Simulation Study

Abstract

This research addresses a comprehensive particle-based simulation study of the structural, dynamic, and electronic properties of the liquid-vapor interface of methanol utilizing both ab initio (based on density functional theory) and empirical (fixed charge) models. Numerous properties such as interfacial width, hydrogen bond populations, dipole moments, and correlation times are characterized with identical schemes to draw useful conclusions on the strengths and weakness of the proposed models for the interface of neat methanol. Our findings indicate that all models considered in this study yield similar results for the radial distribution functions, hydrogen bond populations, and orientational relaxation times. Significant differences in the models appear when examining both the dipole moments and surface relaxation near the aqueous liquid-vapor interface. Here, the density functional theory interaction potential predicts a significant decrease in the molecular dipole moment and slight expansion in the oxygen-oxygen distance as the interface is approached. This work was supported by the U.S. Department of Energy's (DOE) Office of Basic Energy Sciences, Chemical Sciences program. The Pacific Northwest National Laboratory is operated by Battelle for DOE. For submission to Journal of Physical Chemistry B