Dear all,

My model is a system consists of 3 kinds of molecules (i.e., 10A + 15B + 12C), and using Materials Studio, I would like to know how to calculate the viscosity of such a mixture?

I am now using Shear task in Forcite, setting temperature to 85C(358K), Compass forcefield, shear rate is 0.1 /ps.  The input .xsd file was first equilibrated after 200ps, and then in Shear process, the dynamic option was set as NVT, 200ps with timestep  1fs.

However, I got a result of around 1 cp, which was far from the data from literature.  We know  1 cp = 0.0001 Pa s, and the data from the literature is nearly 20000cp, the difference is so huge!!

I changed the shear rate, and found that with the decrease of shear rate, the viscosity increased, but the Std. Dev increased a lot.

Therefore what is a preferrable shear rate for calculating the viscosity and whether the Shear task could slove the calculation of mixture viscosity?

Could anyone help me with this?

Thanks in advance.

Regards,

Guangji