MOLECULAR DYNAMICS SIMULATION OF Ca HYDRATION AND THE OPTICAL RESPONSE OF CLUSTERED WATER

Ion hydrates in polar solutions is a rich and multi-discipline topic. Examples can be found in molecular biology topics such as nerve signal transfer, electrolyte transport, nutrient transport through cell walls, and inter-cell communication. Industrial applications such as toxic chemical studies and treatment in ground water, and polar solvent hydration of surfaces. Examples of these are UO2 and U2 hydration in ground water, and MgO surface interaction with polar solvents. The investigation of Ion hydrates directly ties with the properties of bulk and cluster water systems. To understand hydration of materials, the structure of different water systems must be understood. In addition, theoretical calculations of cluster and bulk water behavior is not well understood. The hydration of Ca and CaCl2 is a well known phenomena, and so makes an excellent material for the testing of theoretical models. Well tested quantities include first shell coordination numbers and radial distribution functions. We show that the use of classical molecular dynamic calculations with an single point charge model for water give good agreement with experimental reports by implementing the Groningen Machine for Chemical Simulations (GROMACS) package. Investigation of cluster water in the soft UV range is a difficult experimental and theoretical system to obtain. Edge effects and cluster sizes dominate any calculations, and internal structure greatly shifts any results obtained. The soft UV spectrum of clustered water is investigated using real time-time dependent functional theory calculations with the Spanish Initiative for Electronic Simulations with Thousands of Atoms (SIESTA). It is shown that with an appropriate basis set the soft UV spectrum of cluster water can be accurately calculated. From this, it is possible to calculate the soft UV spectrum of many other systems that interact or are members of clustered water systems.