Analysis of Shear Viscosity and Viscoelastic Relaxation of Liquid Methanol Based on Molecular Dynamics Simulation and Mode-Coupling Theory
Tsuyoshi Yamaguchi, Antonio Faraone
The role of the prepeak structure of liquid methanol in determining its shear viscosity was studied by means of molecular dynamics (MD) simulation and mode-coupling theory (MCT). The autocorrelation function of the shear stress and the intermediate scattering functions at both the prepeak and the main peak were calculated from the MD trajectories. Their comparison based on MCT suggests that the viscoelastic relaxation in the ps regime is affected by teh slow structural dynamics at the prepeak. On the other hand, the MCT for molecular liquids based on the interaction-site model (site-site MCT) fails to describe the coupling between the prepack dynamics and shear stress. The direct evaluation of the coupling between the two-body density and the shear stress reveals that the viscoelastic relaxation is actually affected by the prepack dynamics, although the coupling is not captured by the site-site MCT. The site-site MCT works well for a model methanol without partial charges, suggesting that the failure of the site-site MCT originates inform the existence of a hydrogen-bonding network structure.
and Faraone, A.
Analysis of Shear Viscosity and Viscoelastic Relaxation of Liquid Methanol Based on Molecular Dynamics Simulation and Mode-Coupling Theory, Journal of Chemical Physics, [online], https://tsapps.nist.gov/publication/get_pdf.cfm?pub_id=923385
(Accessed December 10, 2023)