Temperature keeps increasing during nvt/nve relaxation period

LAMMPS LAMMPS Beginners
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(1) I have simulated laser melting of powder particle, wherein the plate was kept constant using a Langevin thermostat while a layer of powder was added as the first layer. Subsequently, the entire system was relaxed by NVT and NVE ensembles (before laser scanning) using the following code

timestep 0.0001

fix relax1 all nvt temp 300.0 300.0 100.0
run 10000
unfix relax1

timestep 0.0001

fix relax2 all nve
run 5000
unfix relax2

I’m encountering an issue where the temperature of the layer continues to rise during the relaxation period, as shown in the graph. Is there a method to maintain the layer temperature around 300K prior to laser scanning? I tried to use Langevin thermostat on layer, but the temp keeps rising.

image
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(2) Also, atoms appear suspended (in the simulation box) during scanning (fix heat method), is it normal ? I was expecting them to melt and settle, thereby reducing the height of the powder layer

image

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There is not enough information here for a meaningful assessment.

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Is it ok if I share the input and log file via email?

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No. I am volunteering my time here so that everybody can learn from it.

Besides, without explanations about the details of the research and why certain choices were made, it may be difficult to understand what your input is about. Just dumping input and log on people without context is almost as bad as your original post.

If you want a personal/private consultation with me you have to either convince me to become a collaborator on your research or to work as a contracted consultant. Neither is very likely from what I have seen so far.

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