How to define a constrained MD path (IRCCAR)?

[kgsteen]

Hello,

The ICONST page has recently been updated with two new flags (IS and IZ), which (seemingly) allow the definition of a discretised constrained MD path. At present, the link to the IRCCAR file is broken or missing.

Is this capability (defining a discretised MD path) currently available in VASP?
If so, which version?
If so, could you provide an example IRCCAR file?

Thank you!

[mike_foster]

I don't know anything about this feature, but you can see how the file is read starting on line 433 in src/internals.F (VASP6.3.2).

[fabien_tran1]

Hi,

Explanation will soon be added on the VASP wiki. We will let you know.

[kgsteen]

Great - thank you!

[jorge_laranjeira]

Hi,

I'm trying to use some complex coordinates in advances MD where I need to set up this file and there is no wiki entry yet.
Can you please explain how we should set up this file?

[rwindiks]

An example:

ICONST:

R 1 2 0
R 3 4 0
IS 2*ci 0
IZ 2*ci 8

IRCCAR:

2
1.0 3.0
2.0 1.5

Use a harm. bias potential to maintain a value of IZ around zero. Evolve IS with a slow growth dynamics (INCREM), with a harm. bias potential, or with metadynamics.

[rwindiks]

You might also want to go through the supporting information of https://doi.org/10.1021/acscatal.4c00736.