Single Water Entropy : Implementation and Analysis on Supercooled Water

Abstract

The calculation of solvent entropy from a molecular dynamics simulation remains to be a challenge due to the difficulty of sampling the large phase space of even a small system of 1000 water molecules in realistic time scales. This motivates the search for good approximations for the same, Single Water Entropy (SWE) being the approach adopted in this thesis. The initial work involved the implementation of the SWE calculator in C++ and further testing on the system of supercooled water. The insight of an entropy estimate at a single particle level is used to analyze HDL and LDL phases. From the fluctuations in SWE at lower temperatures, their relation to structural polymorphism was studied with the help of structural order parameters. To validate the approach of SWE and to see if the approach conserves configurational entropy, the same approach was applied to an ideal monoatomic gas system which showed that the entropy estimate by SWE was able to capture the nature of the ideal gas entropy trends.