Integrated Simulation System for Soft Materials.

Viscosity can be evaluated through calculation of shear deformation using Lees-Edwards boundary conditions.

Results for n-decane and n-hexadecane are shown below. Using the Full Atomistic model created with J-OCTA, the calculations were carried out with conditions of density 0.613 [g/cm3] and temperature 480 K for n-decane, and density 0.753 [g/cm3] and temperature 323 K for n-hexadecane. The number of molecules in the system was 200 and 100 respectively. Viscosity was evaluated while varying the shear rate from 1e+12 [1/s] to 1e+10 [1/s]. VSOP was used for the molecular dynamics calculations (Fig. 1).

Fig. 2 shows a double logarithmic plot of calculated viscosity against shear rate. It can be seen that viscosity increases with decreasing shear rate, but for n-decane, viscosity approaches a constant value when shear rate is 1e+10 [1/s] or below.

In the viscosity evaluation using the Green-Kubo method in Reference [1], under similar conditions, viscosity of n-decane is 0.178 [e-3 Pa·s] and viscosity of n-hexadecane is 1.17 [e-3 Pa·s].