PhD Defence by Aswin Vinod Muthachikavil
”Structureand Properties of Water”
Although we take water’s anomalies for granted, the existence of life on earth is heavily dependent on these strange properties of water. Water can store much more heat than most other liquids, exhibits a non-monotonic temperature dependence of density, high surface tension- all of which supports life on our planet. The main reason behind water’s anomalies is believed to be the existence of local environments in liquid water. Recent developments in the science of water suggests two local environments in liquid water, that can separate into two different phases when sufficiently super-cooled. This strange hypothesis was experimentally proven only recently because of the difficulty in conducting experiments at temperatures so cold, that water does not stay as a liquid.
Molecular simulation is therefore a good tool to explore water at such conditions where experimental analysis is difficult. Recent simulations have shown that there is a bomodailty in the distribution of local structure in water indicating the existence of two structures. One of the structures is predominantly tetrahedral (often called the locally favored tetrahedral structures, or LFTS), and the other is dirordered like a normal liquid, without particular particular structure (often called the de structured normal liquid structure or DNLS).
This study uses molecular simulations to identify these local structures in liquid water. Computational methods are used to identify hydrogen bonds and study the local environments in water. Different methods that are laid out in the literature are compared with a method that was developed during this study. It is also explored if we can mathematically explain the anomalous behaviour of water by making use of the new knowledge of the local environments in water.
Molecular simulation is therefore a good tool to explore water at such conditions where experimental analysis is difficult. Recent simulations have shown that there is a bomodailty in the distribution of local structure in water indicating the existence of two structures. One of the structures is predominantly tetrahedral (often called the locally favored tetrahedral structures, or LFTS), and the other is dirordered like a normal liquid, without particular particular structure (often called the de structured normal liquid structure or DNLS).
This study uses molecular simulations to identify these local structures in liquid water. Computational methods are used to identify hydrogen bonds and study the local environments in water. Different methods that are laid out in the literature are compared with a method that was developed during this study. It is also explored if we can mathematically explain the anomalous behaviour of water by making use of the new knowledge of the local environments in water.