DECANE UNDER SHEAR - A MOLECULAR-DYNAMICS STUDY USING REVERSIBLE NVT-SLLOD AND NPT-SLLOD ALGORITHMS

In a recent article [J. Chem. Phys. 102, 3376 (1995)] molecular dynamics (MD) was used to calculate the shear viscosity of liquid n-decane using an intermolecular potential that reproduces the liquid-vapor coexistence as well as the critical temperature. Semi-quantitative agreement with experiment was obtained. To further test the model, n-decane is examined under shear using reversible nonequilibrium molecular dynamics (NEMD) in both the isothermal-isobaric (NPT) and the canonical (NVT) ensembles. The algorithm proposed herein, for studying a molecular system, is an atomic version of the so-called SLLOD algorithm originally introduced by Edberg, Evans, and Morriss [J. Chem. Phys. 84, 6933 (1986)]. Results obtained by Daivis and Evans [J. Chem. Phys. 100, 541 (1994)] indicating the disappearance of a high shear-rate (gamma) thickening regime when the simulations are performed in the NPT ensemble are corroborated. The ''plateau'' region, where the viscosity is essentially independent of shear-rate, gamma is examined in detail in order to interpolate back to the Green-Kubo value. (C) 1995 American Institute of Physics.