Deriving thermal conductivity from outputs of Muller/Plathe method

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1

Dear users,

I have reviewed the examples on calculation of thermal conductivity in lammps package and also reviewed few available numerical examples in lammps forum. Still I am confused and do not know how to extract the thermal conductivity from outputs of fix thermal/conductivity.

For example, do I have to multiply number of atoms by exchanged kinetic energy? If we have a bilayer graphene system then what is the thickness? is it the whole z direction or only 2*thickness of one graphene layer?

How the elapsed time is calculated? A numerical derivation would be extremely helpful.

Thanks.

Best regards,

Nima Pirouzmand

2

The file examples/KAPPA/README explains exactly how

a value was extracted from each of the 3 inputs scripts (and

their output) in that dir.

Steve

3

Prof. Plimpton,

You are right.I did not attention to that file before.

Thank you.

Best regards,

Nima Pirouzmand

4

The thickness of a 2D material in classical molecular dynamics with point-like particles is ill-defined. Different authors use different (arbitrary for that matter) references, which is pretty messy. For a single layer of graphene, you can for example use a thickness based on the range of your potential, the amplitude of the vibrations, or something like twice the carbon van der Waals radius (2*1.7 A) - for a bilayer, look at what people are using in the literature. You have to be careful with what you are comparing your result if you choose a reference.

Arthur

5

Dear Arthur,

Thank you very much for your informative response.

Best regards,

Nima Pirouzmand