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Author Domaros, Michael von ♦ Kirchner, Barbara ♦ Jähnigen, Sascha ♦ Friedrich, Joachim
Source United States Department of Energy Office of Scientific and Technical Information
Content type Text
Language English
Subject Keyword 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
Abstract 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 known hydrogen bond network preferences of neat NMF.
ISSN 00219606
Educational Use Research
Learning Resource Type Article
Publisher Date 2016-02-14
Publisher Place United States
Journal Journal of Chemical Physics
Volume Number 144
Issue Number 6


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