A simple two-dimensional model was used to describe the (anomalous) properties of wa-ter. The advantages of such a model are mainly the increased computational efficiency, the simple visualisation of the system and the suitability for use in statistical-mechanical theories. We used the rose model and Mercedes-Benz model, in which the molecules are modelled as Lennard-Jones discs with explicit orientation-dependent potentials for the hydrogen bonds. The aim of the research was to investigate the properties of the rose model in different systems and furthermore to develop approaches that allow us to calculate the properties of (liquid) water as fast as possible. We used simulations to determine the anomalous regions of the rose model and organise them into a hierar-chy. This hierarchy differs from that of real water and depends on the parameterisation of the model. Another important anomalous property of water is its diverse phase behaviour. Using thermodynamic perturbation theory, we determined the liquid-vapor coexistence line and percolation line. More phase transitions were determined using the nested sampling algorithm. However, since we wanted to determine the phase diagram as simply as possible, we developed an approach that virtually automatically determines the complete phase diagram of the water model using unsupervised machine learning methods. Using molecular dynamics simulations, we investigated the behaviour of the rose water model in static and time dependent electric fields. In a strong field the water molecules lose all the properties of water and behave like dipoles in an electric field. However, when the field strength is approximately equal to the strength of the hydrogen bonds, the anomalous properties of water become even more pronounced. We have developed a model that describes the frequency response of water to an time dependent electric field based on the statistics of the hydrogen bonds. We have also developed a structural model of water based on an analytical model of water. The model generates snowflake-like structures that serve as an approximation of the structure of liquid water. The analytical model has thus been developed into a complete model that enables the calculation of the thermodynamic, dynamic and structural properties of water.
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