Yeonsik, what sort of energies would your incoming ions have? I'd worry if the energies were quite large, for at least 2 reasons.

1) The core level electrons in the POTCARs are included in a static manner, they don't shift. But ions with high energy might approach each other at very small distances. In real life, the core levels would then start to shift (broaden from being just discrete lines to bands of some width). This effect would not be properly included in most or all types of VASP calculations.

2) If your ions are very fast moving, the Born-Oppenheimer approximation (which treats electrons as if they are always in the ground state, usually true since electrons are so much lighter than the nuclei) used in VASP may no longer be adhered to. Ions might be moving as fast as electrons usually are.

You might want to check if ion bombardment would be realistic to model with a ground state DFT method and potentials with frozen core level electrons.

Hello Yeonsik,

Actually I nerer try to do anything like you wish to do but it is possible to set velocity by the mean of the POSCAR. Indeed you shall have at least in your POSCAR informations about your cell (dimension, vectors ...) at least the number of each atoms ( in the same order that you provide potential in the POTCAR) and the coordinates of the atoms system (either in direct or cartesian coordinates plus the precision on the freedom degree of each atom).

Most of the POSCAR finish here, but you can write the velocity ( in angs/fs) in each direction for each atoms right after their coordinates. As for the atoms coordinates it will be a matrix Nb(atoms) x 3

You might change a bit your INCAR using SMASS and provide a different value for IBRION, and probably pay attention to the POTIM value.

Also, you should think about the temperature, as the bombarding ion will provide energy to the other atoms of the system.

Some elements of reflexion here :

http://cms.mpi.univie.ac.at/vasp/vasp/Advanced_MD_techniques.html

http://cms.mpi.univie.ac.at/vasp/vasp/Molecular_Dynamics.html

http://cms.mpi.univie.ac.at/vasp/vasp/SMASS_tag.html#incar-smass

http://cms.mpi.univie.ac.at/vasp/vasp/TEBEG_TEEND_tag.html#incar-te

Yeonsik, what sort of energies would your incoming ions have? I'd worry if the energies were quite large, for at least 2 reasons.

1) The core level electrons in the POTCARs are included in a static manner, they don't shift. But ions with high energy might approach each other at very small distances. In real life, the core levels would then start to shift (broaden from being just discrete lines to bands of some width). This effect would not be properly included in most or all types of VASP calculations.

2) If your ions are very fast moving, the Born-Oppenheimer approximation (which treats electrons as if they are always in the ground state, usually true since electrons are so much lighter than the nuclei) used in VASP may no longer be adhered to. Ions might be moving as fast as electrons usually are.

You might want to check if ion bombardment would be realistic to model with a ground state DFT method and potentials with frozen core level electrons.

Dear Yeonsik,

   A word of caution:

In case you situation fits into the BOMD setup (as mentioned by Peter, above),

please make sure that your POTIM (timestep) is compatible (small enough) with the velocities of ions provided in the POSCAR.

how to set the velcocities of one atom in POSCAR?