Comparison between fix heat and ehex

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1

Hi LAMMPS Team,

I ran two separate simulations, heating all atoms of a Au nanoparticle (AuNP) in a gold NP - water system using both fix heat and fix ehex commands. In both simulations, I thermostat the water using a region defined at a fixed distance away from the AuNP. Results show that I am get a difference of 200 K in the temperature distribution in the AuNP (see attached file illustrating the comparison). Both simulations use the EAM potential for gold.

Please help me understand the following:
(1) Why is there such a big difference in the temperature distribution between the two fix algorithms (heat and ehex)?
(2) How can I benchmark the results and justify the use of a particular kind of fix?

fig_cmp_heat-ehex.png

2

I don’t know. If you read the 2 doc pages for heat and ehex,

the latter is supposed to reduce energy drift. Not enough

info to say whether that is an issue with your simulations.

I suggest you contact the author of fix ehex to ask his opinion.

Its Peter Wirnsberger, as listed in the doc page for fix ehex.

Steve