Give initial velocity in POSCAR for Ab Initio Molecular Dynamics

[Seunghwan_Kwon]

Hello,

I have a question related to Ab Initio Molecular Dynamics (AIMD).

I know that the velocity of each atoms are written in POSCAR after the execution of AIMD.

I wonder that is it possible to give initial velocity to the specific atoms in AIMD simulation?

I typed velocity of specific atoms in initial POSCAR and executed AIMD simulation

because in my AIMD simulation, some atoms initially have very high initial velocity physically.

However, since time scale of AIMD is limited to about a few picosecond,

artificially giving initial velocity of atoms seems not reasonable.

My point is, is it OK to artificially give initial velocity to specific atoms using POSCAR in AIMD simulation?

Thank you.

[henrique_miranda]

In principle, there is no issue with giving an initial velocity to atoms when you are running an AIMD simulation.
What you need to keep in mind is that the configuration you start with is unlikely to be an equilibrium configuration.
Also, the time step you use (POTIM) might need to be small if the velocity is high.

If would like to have an equilibrium configuration (positions and velocities) I would recommend not setting initial velocities in your POSCAR file
https://www.vasp.at/wiki/index.php/POSCAR
and selecting an adequate temperature for your simulation using TEBEG
https://www.vasp.at/wiki/index.php/TEBEG

Then you need to run the simulation for enough time for the temperature to equilibrate.