Vapor–liquid equilibria of water from first principles: comparison of density functionals and basis sets

Abstract

Gibbs ensemble Monte Carlo simulations were run with an efficient mixed-basis electronic structure method to explore the phase equilibria of water from first principles using Kohn–Sham density functional theory. The Perdew–Burke–Ernzerhof exchange/correlation density functional gives a higher critical temperature (700 K) and boiling point (480 K) than experiment, although good agreement is found for the saturated liquid densities. A systematic increase in the size of the basis set for the Becke–Lee–Yang–Parr exchange/correlation density functional from a double-ζ to quadruple-ζ split valence leads to further deviations from experiment on the saturated liquid and vapor densities, while the intermediate basis set gives the best results for the heat of vaporization at T = 423 K. Analysis of the liquid structure for all simulations shows changes that can partially be explained by the different densities at a given temperature, and both density functionals show a similar temperature dependence of the liquid structure.

Keywords:

• Monte Carlo
• Density functional theory
• Phase equilibria
• Water

Acknowledgements

We thank Larry Fried and Charlie Westbrook for their ongoing support of this work. We also thank Juerg Hutter, Joost VandeVondele, Matthias Krack, Erin Dahlke, and Bin Chen for many stimulating discussions. Financial support from the National Science Foundation (CTS-0553911), a 3M Foundation Graduate Fellowship (M.J.M.), and a Department of Energy Computational Science Graduate Fellowship (M.J.M.) are gratefully acknowledged. Part of this work was performed under the auspices of the U.S. Department of Energy by the University of California Lawrence Livermore National Laboratory (LLNL) under contract No. W-7405-Eng-48. Computer resources were provided by Livermore Computing and the Minnesota Supercomputing Institute.