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Title: Quantum cluster equilibrium model of N-methylformamide–water binary mixtures

The established quantum cluster equilibrium (QCE) approach is refined and applied to N-methylformamide (NMF) and its aqueous solution. The QCE method is split into two iterative cycles: one which converges to the liquid phase solution of the QCE equations and another which yields the gas phase. By comparing Gibbs energies, the thermodynamically stable phase at a given temperature and pressure is then chosen. The new methodology avoids metastable solutions and allows a different treatment of the mean-field interactions within the gas and liquid phases. These changes are of crucial importance for the treatment of binary mixtures. For the first time in a QCE study, the cis-trans-isomerism of a species (NMF) is explicitly considered. Cluster geometries and frequencies are calculated using density functional theory (DFT) and complementary coupled cluster single point energies are used to benchmark the DFT results. Independent of the selected quantum-chemical method, a large set of clusters is required for an accurate thermodynamic description of the binary mixture. The liquid phase of neat NMF is found to be dominated by the cyclic trans-NMF pentamer, which can be interpreted as a linear trimer that is stabilized by explicit solvation of two further NMF molecules. This cluster reflects the knownmore » hydrogen bond network preferences of neat NMF.« less
Authors:
;  [1] ;  [2] ;  [3]
  1. Mulliken Center for Theoretical Chemistry, Universität Bonn, Beringstr. 4, D-53115 Bonn (Germany)
  2. Martin-Luther-Universität Halle-Wittenberg, von-Danckelmann-Platz 4, D-06120 Halle (Germany)
  3. Technische Universität Chemnitz, Straße der Nationen 62, D-09111 Chemnitz (Germany)
Publication Date:
OSTI Identifier:
22493732
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Chemical Physics; Journal Volume: 144; Journal Issue: 6; Other Information: (c) 2016 Author(s); Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL AND ANALYTICAL CHEMISTRY; AQUEOUS SOLUTIONS; BENCHMARKS; BINARY MIXTURES; COMPARATIVE EVALUATIONS; DENSITY FUNCTIONAL METHOD; EQUILIBRIUM; FORMAMIDE; HYDROGEN; ITERATIVE METHODS; LIQUIDS; MEAN-FIELD THEORY; MOLECULES; SOLVATION; WATER; YIELDS