First nvt then nve energy is not constant

LAMMPS LAMMPS General Discussion
1

Hello, teachers. My model is a catalytic model. The substrate is CeO2 and the catalytic particles are palladium clusters. Now I want to simulate the heat transfer between the particles and the substrate. I use nvt to control the particle and substrate temperatures at 800 and 400K respectively. After running for a while, I put the whole system under the nve ensemble to simulate the heat transfer. However, from the results, the total energy of the system under the nve ensemble is constantly decreasing, and the temperatures of the palladium particles and the cerium oxide substrate are also constantly decreasing and tending to zero. I think the temperature of the cerium oxide substrate should increase, and the two temperatures should be stable at one value. Please help me see if my in file is written correctly. Thank you in advance.
11
in.file (1.4 KB)
noVo.data (141.6 KB)
slurm-14440236.out (56.3 KB)

2

Hi @yfyin,

some comments.

  • Please have a read on the forum guidelines to get hints on where to look at to understand your issue and add the relevant details to your problem if needed.
  • You do not provide the LAMMPS version you use but the slurm file start stating this is the 31 Aug 2021 version. This is a very old version and your script would not run on a more recent LAMMPS executable since the reaxff package has add significant changes and bug correction since the new releases.
  • As is, it is impossible to reproduce your simulation since you do not provide the potential file you are using nor state where it comes from.
3

Hello, teacher. I am using LAMMPS (31 Aug 2021). All my files are given below. I hope you can give me some advice. Thanks in advance.
in.file (1.4 KB)
noVo.data (141.6 KB)
PdCHOCe.field (12.9 KB)

4

Why use Reaxff force fields for that?

Do Reaxff force fields conserve energy? I don’t think they do.

5

Professor, do you have any basis for saying this? I am a novice and would like to hear more advice from you. Why can’t the reaction force field simulate this situation?

6

I am no reaxff expert. Just search for “reaxff energy conservation” on google scholar, you will see that there have been plenty of studies concerning these aspects.