Viscosity of isotropic system

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GROMACS version: 5
GROMACS modification: No
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Hi

I have a anisotropic system and I am trying to obtain shear viscosity from ‘tcaf’ method.
Is the result I get in this method using Gromacs is the ‘‘averaged’’ viscosity? or the obtained viscosity depends on the isotropicity I have applied (uniform electric filed to the system in one direction)?

thanks for answer

3

When you apply an electric field you might get anistropic dynamic behavior and also anistropic viscosity. gmx tcaf averages over vectors with many different orientations, so you will get an average.

If you want the viscosity parallel and perpendicular to the field, you can use cosine acceleration. Even better is the new deform setup that generates a proper Couette flow, but for that you would have to get the latest GROMACS development version from gitlab.