| The study of the energy landscape of liquid systems provides important information on the underlying structure and properties these systems. Although the energy landscape of a system is defined by its volume and number of particles, its curvature can be distorted by the use of effective stresses that will lead to changes in the properties of the system.; Three projects that use molecular simulations to study the effect that these distorting mechanisms have on the shape of the energy landscape and the properties of the system will be addressed. The first project tests whether the disordered packing configurations that are stable in soft potential systems are also stable in hard potential systems, and vice versa. Here, the properties of packing configurations corresponding to energy minima are examined as the steepness of the interparticle potential changes. Normal mode analysis shows that energy minima flatten out and disappear as the steepness of the potential changes. Thus packing configurations that are stable for a soft potential system are not stable for hard potential systems, and vice versa.; The second project addresses the density-driven glass transition in a system of anisotropic particles. Here, glasses with isotropic orientational order are heated to a temperature T, and the relaxation times by which nematic orientational order develops are determined. These relaxation times diverge at a critical density rhoc; i.e., the system can equilibrate at rho < rhoc, but it cannot equilibrate at rho > rho c (at T). The relaxation times follow a power-law scaling as the critical density is approached, suggesting that this density-driven glass transition concurs with the mode coupling theory.; Finally, the flow behavior of a liquid composed of particles with rod-like shapes is modeled. The simulations determine the order parameter, viscosity and diffusivity of constrained and unconstrained system as a function of shear rate. The changes in the transport properties seen in both types of systems are related to the changes in orientation of the particles under shear flow. A shear-induced orientation mechanism as well as a shear-activated dynamics mechanism are identified as being responsible for the changes in the transport properties of anisotropic system. |
