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Dear VASP developers,

I was wondering if there are plans to implement a selective cell relaxation (like only "a", "b", "c", or in-plane only for 2D material) - similar to the following method:
https://github.com/Chengcheng-Xiao/VASP_OPT_AXIS

It is just very annoying to patch every new version of VASP with this and recompile every time. And since the format/content of the VASP's files changes from one release to another, this patch may not work in the future.

Thank you.

Dear sergey_lisenkov1,

I am not sure if I understand your question correctly. But what you want
to do is to constrain certain lattice vectors during cell shape relaxation with vasp.
As far is I know and understand your question this feature is available in vasp and is documented
here
wiki/index.php/ICONST

under the header Restrictions on the volume and/or shape of the simulation cell.
I hope this helps and that this is the feature your are looking for.


All the best

Jonathan

Hi Jonathan,

Thanks for your reply. I'm sorry if my original message wasn't clear.

What I meant is "constrained cell relaxation", something like explained in the "constr_cell_relax.F" file, but for more general use, without recompiling every time.

I will check ICONST settings and how they applied. If you are familiar with it, can it be used to do full relaxation (cell+ionic) of 2D material (no cell relaxation along third lattice vector)?

Thanks,
Sergey

Dear sergey_lisenkov1,

Yes this should be possible. To constrain the length of the third lattice vector you just have to put into your ICONST file. To additionally constrain the angle of the third lattice vector with respect to the second and first you have to add But this works only in combination with IBRION=0.
Another feature which might be interesting for you and which is working for IBRION>0 is the INCAR tag LATTICE_CONSTRAINTS:
wiki/index.php/LATTICE_CONSTRAINTS

And last I would like to recommend this post to you, which might also be helpful:
forum/viewtopic.php?f=4&t=18723&p=22915#p22915

All the best Jonathan

Hello,

it seems that all these options are only used for MD simulations. But i'm mostly interested in geometry relaxation (IBRION = 2).

Dear sergey_lisenkov1,

I think this is a miss-understanding. Both links I sent to you are meant for structure relaxation. So they are usable with IBRION=2. Especially check the link https://www.vasp.at/forum/viewtopic.php ... 915#p22915 there was some update until our last
conversation. The more sophisticated feature for relaxation mentioned in this post will become available in future vasp version.

Best Jonathan