Now I am facing problem with relaxing the system to certain temperature under npt ensemble. The following is what the paper describes about equilibrating the titanium crystal
This is my input script
What is the possible reason behind getting different results? Any help would be much appreciated. Thank you.
Your time constant for the thermostat in your input is set to 100ps, yet you are running for only 50000 steps of 0.1fs i.e. 5ps. That is too long a time constant for too short a trajectory.
The reference plot shows at least 20ps relaxation and the temperature has recovered after about 1-2ps, which suggests a thermostat time constant no more than 1ps. Please see the documentation of fix npt for a discussion on how to choose the time constants.
I changed the order of the command. This command effects the subsequent commnds if I am not wrong
Is there any chance that this behavior is related to the pair coefficients file?
That has nothing to do with your issue. The problem is in the science and the values you input. They don’t make sense and cannot work as you expect. LAMMPS is doing exactly what you are asking it to do. So the logical conclusion is that you are not understanding the real problem and my explanations. You have posted your update in less than 10 minutes since my reply. Nobody can properly read and understand this in such a short time.
No. This is a PEBCAK type of problem.
Okay I apologise. I thought timestep command effects the script globally. So 100*0.1 = 10fs. Now its working after editing the tdamp to .1.
Big thanks for your time even though you got annoyed. Sorry again.
Don’t guess in these cases. That is why I suggested to read the documentation. I am doing this for a reason, not just to annoy people. Compared to other scientific software, LAMMPS has a very detailed documentation, so it is worth spending the time reading it.
