Nonequilibrium structural changes of a viscoelastic liquid under oscillatory shear: A molecular dynamics study

The structural changes of a concentrated liquid under an oscillatory shear are investigated by nonequilibrium molecular dynamics simulations. In simulations starting from a liquid, two successive structural changes to layered structures are reproduced, which corresponds well with the experiments by Ackerson and Pusey [Phys. Rev. Lett. 61, 1033 (1988)]. The nonequilibrium phase diagrams in the space of the frequency, the shear rate, and the number density are also obtained. The nature of the transition from a liquid to ordered structures changes with the frequency. The shear-induced melting is observed at low frequency, while the shear-induced freezing occurs at high frequency. We also find that the behavior of the viscoelastic properties near the shear-induced freezing line is well described by the Maxwell viscoelastic model. {} 1996 The American Physical Society.