Heat capacity of a Lennard-Jones fluid using LAMMPS

Science Talk
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As an introduction to molecular dynamics, I am using LAMMPS via Atomify to compute the heat capacity of a Lennard-Jones fluid.

I have already implemented one method, which exploits the idea that Cv​ corresponds to the slope of the U-T curve.

However, I have encountered an issue with the second method, which relies on energy fluctuations in the canonical ensemble. The results I obtain deviate significantly from the standard values provided by my references. I am using a Nose-Hoover thermostat and working in the canonical ensemble.

It seems to my unexperienced self that energy does not fluctuate enough to get a desirable result. I don’t know where the problem is as I already managed to get it working for the first method.

I attach the results I got trying to compute it using energy fluctuations.

LJ heat capacity 2 method
LJ heat capacity 2 method2013×400 48.8 KB

Cheers

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Your question is not really a question about LAMMPS but about the science of how to compute heat capacity. That makes it off-topic for the LAMMPS categories (the fact that you are using LAMMPS is not sufficient to make it a LAMMPS topic). A better place on MatSci.org to discuss such topics is the “Science Talk” category and thus I will recategorize your topic accordingly.

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