Statistical mechanics of simple and complex fluids

The present dissertation investigates the physical properties of simple and complex fluids using theoretical and computational methods. This work has been focused on three model systems, namely the hard sphere fluid, water and dilute aqueous solutions of non-polar solutes.; The first two studies presented in this dissertation investigate the properties of dilute aqueous solutions of non-polar solutes using a previously published statistical mechanical model. The primary objective in the first study is to examine the effect of adding non-polar solutes (here, simple van derWaals solutes) on mixture response functions, such as the temperature of maximum density, the isobaric heat capacity and the isothermal compressibility. In the accompanying study, the effect of solute addition into solution on the resultant mixture phase behavior is examined. The interest in conducting this investigation is to elucidate the binary mixture phase behavior when one component can have more than one critical point in the fluid phase. The statistical mechanical model from the first study is applied using two parameter sets: one giving rise to a pure component low temperature liquid-liquid transition terminating in a critical point for water (in addition to the normal pure component vapor-liquid critical point); and one where there is no such second critical point. A detailed comparison of mixture phase behavior is conducted of four different non-polar solutes for the two parameter sets.; The third study focuses on the properties of geometrically modified water models. Computer simulations of the Extended Simple Point Charge model of water were conducted using molecular dynamics methods. The effect of perturbing the H-O-H angle in the model on its thermodynamics, dynamics, structure and solvation thermodynamics with respect to non-polar solutes is examined.; The final portion of the present dissertation deals with the development of an extension to the classical scaled particle theory (SPT) of statistical mechanics. The novel extended SPT framework provides a direct route for calculating the structure of the hard sphere fluid in the form of its pair correlation function. Calculation of this central quantity allows for the prediction of other important macroscopic thermodynamic quantities of interest.