Microscopic activated dynamics theory of the shear rheology and stress overshoot in ultradense glass-forming fluids and colloidal suspensions

We formulate a microscopic, force-level, activated dynamics-based statistical-mechanical theory for the continuous startup nonlinear shear-rheology of ultra-dense glass-forming hard-sphere fluids and colloidal suspensions in context ECNLE approach. Activated structural relaxation is described as coupled local-nonlocal event involving caging longer-range collective elasticity which controls characteristic stress time. Theoretical predictions deformation-induced mobility enhancement, onset acceleration at low values stress, strain, or shear-rate, apparent power-law thinning steady-state time viscosity, non-vanishing activation barrier shear-thinning regime, an Herschel-Bulkley form rate dependence shear exponential growth different measures dynamic yield flow-stress with packing fraction, reduced fragility heterogeneity under deformation were previously shown to be good agreement experiment. The central new question addressed here defining feature transient response - stress-overshoot. In contrast flow understanding requires explicit treatment nonequilibrium evolution structure, elastic modulus, quantitative model this aspect physically motivated computationally tractable manner. stress-overshoot are experimental observations metastable regime function shear-rate accounting deformation-assisted motion crucial both responses.