Ethylene Glycol in the Liquid State Structure Conformation and Dynamics A Study Using Ab Initio Molecular Dynamics Simulations

Abstract

newline Ethylene glycol (EG) is an important organic molecule with unique properties and a wide range of applications. The EG molecule shares a structural motif with many biomolecules and serves as a part of the training set for parameterizing the molecular mechanics program. It is one of the simplest molecules capable of intra- and intermolecular hydrogen bonding while at the same time exhibiting conformational degrees of freedom. In this thesis ab initio Car-Parrinello molecular dynamics simulations were used to probe the structure, conformation, and dynamics of the ethylene glycol molecule in the liquid state. The three key issues that the thesis wished to address were (i) Can simulations reproduce the results of the Raman study on the molecular conformation of the EG molecule in the liquid, and how are the two - conformation and vibration spectra - related? (ii) How is the hydrogen bond in the strongly associated liquid EG defined, and how does the hydrogen bond geometry and thermodynamics of hydrogen bond formation vary with the conformation of the EG molecule? and (iii) Can hydrogen-bonded motifs or recurrent patterns of hydrogen-bonded association in liquid EG be identified from a search of the ab initio MD trajectories? In summing up, the thesis has addressed these issues with varying degrees of success - some completely, some partially, and some not at all.