[QE-users] Convergence tests for slabs

[Léon Luntadila Lufungula]

Dear QE users,

I'm creating a slab for studying adsorption of small molecules (around 6-8 atoms in length) and want to converge both the slab thickness and vacuum width. However, I don't fully understand how to do this properly... For the convergence of the slab thickness, I was thinking about taking slabs of different thickness and calculating the surface energy and look at when the difference between two consecutive surface energies is smaller than 1 kcal/mol (i.e. chemical accuracy), but I've also heard that you can look at the difference in energy when adding a layer and converging this energy difference to chemical accuracy. Any suggestions on which is the better option? For the vacuum width, I'm confused if you should converge this value on a clean slab or on a slab with a model compound adsorbed onto it. I've been told you should do this on a clean slab, but I would expect that once an adsorbate is bonded onto the surface, the end of the adsorbate might be close enough to the next layer to interact with it, which would make the convergence test obsolete...

I would be most thankful if someone could tell me the correct procedure in this situation!

Thanks in advance and kind regards,
Léon Luntadila Lufungula
Structural Chemistry group
University of Antwerp


-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.quantum-espresso.org/pipermail/users/attachments/20221219/5170a4b0/attachment.html>