Molecules of motion: Two tales

Abstract

This thesis, ‘Molecules of Motion: Two Tales’, as the title implies explores two challenging problems in chemistry. Both the studies are theoretical investigations that incorporates computer simulations instead of laboratory experiments to solve those problems. However, the main goal as a computational chemist is to provide useful insights to experimentalists to address these challenges with less effort. The first chapter provides a brief introduction on the main topics related to both projects described in chapters 2 and 3. The second chapter focuses on a computational approach to study solvation of rare earth elements (REE) in room-temperature ionic liquids (RTILs). REEs are used in many fields but are considered critical materials due to the challenges in separating them from one another due to their chemical similarities as well as for their need in technology. Nowadays, RTILs have attracted attention in REE separation due to their unique physiochemical properties and environmental friendliness. This work mainly focuses on using both molecular dynamics (MD) and density functional theory (DFT) to study the solvation of two REEs in two different RTILs. The third chapter focuses on a preliminary study to test a novel approach to predict thermochemistry data. Knowledge of thermochemistry of chemical species is very important and accurate thermochemistry data is not readily available for many molecules. Therefore, the development of novel computational approaches to predict these properties is very important. On the other hand, Møller−Plesset (MP) theory is a common perturbative quantum chemical approach that usually uses Hartree Fock (HF) reference orbitals. In this study we tested DFT orbitals in MP calculations to predict the atomization energies of some molecules consisting of second row elements and hydrogen. Finally, the last chapter provides a conclusion on both the projects and future directions.