zur Erlangung des Grades

Water is one of the most frequently studied fluids on earth. In this thesis, water was investigated at two resolutions using multi-scale computer simu-lation techniques. First, the atomistic and coarse-grained resolutions were studied separately. In the atomistic resolution, a water molecule is described chemically by three atoms, while in the coarse-grained case, a molecule is modeled by a sphere. In this work, various coarse-grained models have been developed using different coarse-graining techniques, mainly iterative Boltzmann inversion and iterative inverse Monte Carlo, which are structure-based approaches that aim to reproduce distributions, such as the pair distribution functions, of the atomistic model. In this context the Versatile Object-oriented Toolkit for Coarse-graining Applications (VOTCA) was developed. It was studied to which extent the coarse-grained models can simultane-ously reproduce several properties of the underlying atomistic model, such as thermodynamic properties like pressure and compressibility or structural properties, which have not been used in the coarse-graining process, e. g. the tetrahedral packing behavior, which is responsible for many special properties of water. Subsequently, these two resolutions were combined using the adaptive res-olution scheme, which combines the advantage of atomistic details in a small cavity of high resolution with the computational efficiency of the coarse-grained model in order to access larger time and length scales. In this scheme, the introduced coarse-grained models were used to study the influence of the hydrogen bonds on the hydration of small fullerenes. It was found that the interface structure is more dependent on the nature of the interaction be-tween the solute and water molecules than on the presence of the hydrogen bond network. III I