title: Liquid Methanol from DFT and DFT/MM Molecular Dynamics Simulations.
abstract: We present a comparative study of computational protocols for the description of liquid methanol from ab initio molecular dynamics simulations, in view of further applications directed at the modeling of chemical reactivity of organic and organometallic molecules in (explicit) methanol solution. We tested density functional theory molecular dynamics (DFT-MD) in its Car-Parrinello Molecular Dynamics (CPMD) and Quickstep/Born-Oppenheimer MD (CP2K) implementations, employing six popular density functionals with and without corrections for dispersion interactions (namely BLYP, BLYP-D2, BLYP-D3, BP86, BP86-D2, and B97-D2). Selected functionals were also tested within the two QM/MM frameworks implemented in CPMD and CP2K, considering one DFT molecule in a MM environment (described by the OPLS model of methanol). The accuracy of each of these methods at describing the bulk liquid phase under ambient conditions was evaluated by analyzing their ability to reproduce (i) the average structure of the liquid, (ii) the mean squared displacement of methanol molecules, (iii) the average molecular dipole moments, and (iv) the gas-to-liquid red-shift observed in their infrared spectra. We show that it is difficult to find a DFT functional that describes these four properties equally well within full DFT-MD simulations, despite a good overall performance of B97-D2. On the other hand, DFT/MM-MD provides a satisfactory description of the solvent-solute polarization effects with all functionals and thus represents a good alternative for the modeling of methanol solutions in the context of chemical reactivity in an explicit environment.
authors.affiliation: Université Joseph Fourier Grenoble I, CNRS UMR-5250 Département de Chimie Moléculaire, 301 rue de la Chimie, 38041 Grenoble Cedex 9, France.
authors.forename: Nicolas
authors.initials: N
authors.lastname: Sieffert
authors.affiliation: EaStCHEM School of Chemistry, University of St. Andrews, North Haugh, St. Andrews, Fife KY16 9ST, United Kingdom.
authors.forename: Michael
authors.initials: M
authors.lastname: Bühl
authors.affiliation: Université d'Evry val d'Essonne, LAMBE UMR8587 Laboratoire Analyse et Modélisation pour la Biologie et l'Environnement, Blvd F. Mitterrand, Bat Maupertuis, 91025 Evry, France.|Institut Universitaire de France (IUF), 103 Blvd St Michel, 75005 Paris, France.
authors.forename: Marie-Pierre
authors.initials: MP
authors.lastname: Gaigeot
authors.affiliation: EaStCHEM School of Chemistry, University of Edinburgh, King's Buildings, West Mains Road, Edinburgh, EH9 3JJ, United Kingdom.
authors.forename: Carole A
authors.initials: CA
authors.lastname: Morrison