The knowledge of colloidal suspension rheology is essential for developing their applications. These suspensions, composed of microscopic particles that are dispersed in a solvent, exhibit complex and length scale-dependent viscoelastic behavior. Our group has developed two molecular dynamics (MD) simulation methods to determine the viscoelastic properties of colloidal suspensions: 1) Translational probe rheology, involving the application of an oscillatory force to a probe particle embedded within the suspension; and 2) Rotational probe rheology, involving the application of oscillatory torque to a probe particle. In both approaches, the viscoelastic modulus of the suspension is obtained by analyzing the simulation data for probe motion using continuum theory. In this study, we present a systematic comparison of these two simulation methods for determining the viscoelasticity of colloidal suspensions. Specifically, MD simulations are conducted on colloidal suspensions of different volume fractions to characterize their linear viscoelastic response. Non-dimensional formalism is introduced for both translational and rotational probe rheology. A quantitative comparison of the performance of the two techniques will be presented by comparing the probe rheology simulation results with those obtained using nonequilibrium molecular dynamics (NEMD) simulations.
