Exploring the Structure and Properties of Water through Molecular Simulations
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Abstract:
Water is arguably one of the most important substances on our planet. Its structure and properties lay the foundation for the emergence and existence of life as we know it on our planet.
Water exhibits a lot of ‘anomalous properties’ when compared to most liquids and the way water molecules arrange themselves locally has an important role to play in making it anomalous.
Molecular simulations, therefore, becomes an ideal tool for exploring the structure and properties of water in a wide range of states, from deeply super cooled state to ambient liquid state conditions.
It is often argued that formation of locally favoured structures lies at the root of water’s anomalies. Interestingly, the existence of 2 distinct structural environments in water has been observed to lead to a Liquid-Liquid Phase Transition (LLPT) in water.
There has also been evidences in literature for the existence of a Liquid-Liquid Critical Point (LLCP) for water.
Molecular Dynamics (MD) simulations have been employed to look at different molecular level phenomena, like formation and breakage of hydrogen bonds (Figure 1) and ordering of water in the first shell and second shell of neighbours, at different state points on the phase diagram of water.
Different order parameters are utilized to quantify the structural ordering of water molecules and differentiate the structures that form locally in water. An attempt to visualize these structures based on these translational and orientational order parameters is also performed.
References
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