What does the following error mean and how I can fix it?

Hello Every one,

I am writing a DPD code for CNT in water. I am using “atom_style dpd” &&
“pair_style dpd/fdt/energy 2.5 34387” commands. I am also using "
fix 1 all dpd/energy
fix 2 all eos/cv 4.1"

the error I am getting is : Internal temperature <= zero (…/fix_eos_cv.cpp:70)

I am not sure what this error mean and could not find the error in the LAMMPS ERROR MESSAGES.
My data file has the following shape:

 25 atoms
	  0 bonds
		 0 angles

		 2 atom types
		 0 bond types
		 0 angle types

		 0   20     xlo xhi
		 0   20     ylo yhi
		 0   40     zlo zhi


1 1
2 1


1 1    300.0  2.62  9.90  7.00     1
2 1    300.0  0.38  9.18  7.00     1
3 1    300.0  0.38  6.82  7.00     1
4 1    300.0  2.62  6.10  7.00     1
5 1    300.0  4.00  8.00  7.00     1
6 1    300.0  1.38  9.90  9.18     1

Does anyone know what the error I am getting mean and how can I fix it?

Thank you so much.

That you have an “internal” temperature (as particle property) is an integral part of the model you are using. Your system (for whatever reason) has reached a state, which this value has been set to or otherwise become zero or smaller. This is (obviously) unphysical.

There is not enough information here to tell why and thus one cannot suggest a resolution. Most likely is an error in your data file or something is missing in your input or not updating per-atom data correctly etc. All of these things are very specific to the method, so you would need to talk somebody that has developed or significantly used this methodology.

Thank you so much akohlmey. Do you know anybody who has done DPDe (atom_style edpd) method, or DPD energy conservative methos (atom_style DPD)? I am trying to learn this by myself for my PhD thesis. It would be very helpful if I get connected to somebody who has done a similar method previously. Thanks again for your response.

The canonical way would be to study the publications describing or using the method and then contacting the authors of those publications.