Beyond the Gas Phase: Towards Modeling Bulk Ionic Liquids with a Comparison of Density Functional Tight Binding (DFTB) to Density Functional Theory (DFT)

Coal-fired power plants are a leading contributor to the increase in CO2 released into the atmosphere. Alkanolamines are considered a potential solvent to capture this gas post-combustion, however, some disadvantages have been found. A newer class of solvent candidates proposed for this application is ionic liquids. Computational methods are useful for predicting ideal ionic liquid candidates for this application. Since the expense of DFT methods is high with systems above 100 atoms, the DFTB method was used to study ionic liquid systems. This study proved that DFTB could accurately reproduce DFT results of neutral molecules, however, this was not consistently seen in ionic liquid systems. This study also attempts to determine behavior properties of bulk ionic liquids.