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How to define a constrained MD path (IRCCAR)?
Posted: Tue Jan 31, 2023 9:17 pm
by 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!
Re: How to define a constrained MD path (IRCCAR)?
Posted: Fri Feb 03, 2023 5:47 pm
by 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).
Re: How to define a constrained MD path (IRCCAR)?
Posted: Fri Feb 03, 2023 7:32 pm
by fabien_tran1
Hi,
Explanation will soon be added on the VASP wiki. We will let you know.
Re: How to define a constrained MD path (IRCCAR)?
Posted: Fri Feb 03, 2023 10:04 pm
by kgsteen
Great - thank you!
Re: How to define a constrained MD path (IRCCAR)?
Posted: Sat Aug 23, 2025 8:40 am
by 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?
Re: How to define a constrained MD path (IRCCAR)?
Posted: Thu Aug 28, 2025 7:28 pm
by 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.
Re: How to define a constrained MD path (IRCCAR)?
Posted: Sat Aug 30, 2025 6:09 am
by rwindiks
You might also want to go through the supporting information of https://doi.org/10.1021/acscatal.4c00736.