minimisation after temperature increase.

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1

Hii all,

I am working with a BCC single crystal solid. Considering a small simulation box of 35 X 35X 100 unit cells at room temperature and zero pressure. After that I want to preheat my sample to 2100K. For this,

Firstly, I raised the temperature from 300K to 2100K keeping the pressure at 0 using NPT and I achieved it.

And then, ran a NVE ensemble for 60000 steps to equilibrate the system using the given script.

velocity bulk create 300 12345 rot yes dist gaussian
fix equilibration bulk npt temp 300 2100 0.1 iso 0 0 1 drag 10
run 30000
unfix equilibration
fix 1 bulk nve
run 60000

I wanted to know, even after giving a long run of NVE. is it important to minimise the system, by giving a box/relax statement. Or, is NVE taking care of the equilibration of the crystal.

Nidhi.

2

Minimization is the opposite of equilibrating a system at a finite temperature as it will try to relax the system into its 0K state.

I suggest you read up on equilibration in your MD text book and discuss with a local person that has practical MD experience what equilibration means and how to determine whether you are sufficiently close to equilibrium.

I would also call a simulation of 60,000 steps not “long”.

Axel.