Sebastian B. C. Lehmann

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In this study we present the results of a first principles molecular dynamics simulation of a single 1-ethyl-3-methyl-imidazolium chloride [C(2)C(1)im][Cl] ion pair dissolved in 60 water molecules. We observe a preference of the in plane chloride coordination with respect to the cation ring plane as compared to the energetic slightly more demanding on top(More)
In the present study, we employ quantum cluster equilibrium calculations on a small water cluster set in order to derive thermochemical equilibrium properties of the liquid phase as well as the liquid-vapor phase transition. The focus is set on the calculation of liquid phase entropies, from which entropies of vaporization at the normal boiling point of(More)
An extension of the quantum cluster equilibrium theory to treat binary mixtures is introduced in this work. The necessary equations are derived and a possible implementation is presented. In addition an alternative sampling procedure using widely available experimental data for the quantum cluster equilibrium approach is suggested and tested. An(More)
Different cluster sets containing only 2-fold coordinated water, 2- and 3-fold coordinated water, and 2-fold, 3-fold, and tetrahedrally coordinated water molecules were investigated by applying second-order Møller-Plesset perturbation theory and density functional theory based on generalized gradient approximation functionals in the framework of the quantum(More)
A combined experimental and theoretical approach including quantum chemistry tools and computational simulation techniques can provide a holistic description of the nature of the interactions present in ionic liquid media. The nature of hydrogen bonding in ionic liquids is an especially intriguing aspect, and it is affected by all types of interactions(More)
With the aid of the quantum cluster equilibrium method, we calculate thermodynamic properties for a new water cluster set containing 2-fold and additional tetrahedrally hydrogen-bonded water molecules on the basis of accurate correlated electronic structure calculations. The addition of clusters with 4-fold coordinated water molecules leads to an improved(More)
The intermediate bond forces in ionic liquids are investigated from static quantum chemical calculations at various methods and two basis sets. The experimentally observed red-shift of the donor-proton bond stretching frequency due to a bond elongation is confirmed by all methods. Comparing Hartree-Fock to second-order Møller-Plesset perturbation theory,(More)
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