Zero/negative band gap prediction for COF with band gap ~ 2.3 eV

[Nathan Leonard]

Hi everyone,

I am currently trying to predict the band gap of this COF, with a known optical band gap of 2.29 eV. However, I keep predicting a band gap of around 0 eV. While I do not expect an accurate band gap with PBE, I do expect something above 0. This has occured with other COFs I have tried, so I assume there are some issues with my parameters. Any suggestions? I have attached the input, output and CIF file.

Thanks in advance,

Nathan

[Nathan Leonard]

For reference, this is the paper with the COF. https://onlinelibrary.wiley.com/doi/10.1002/anie.202007895

[Krack Matthias]

Hi Nathan

 

It seems that your cif file is not correctly digested by CP2K, because the cell angles in the cif file are not 90 degrees (check the lines tagged with CELL| in the output file). I suggest to define the &CELL and &COORD sections in the CP2K input based on an export from VESTA in the POSCAR file format.

 

HTH

 

Matthias

 

--
You received this message because you are subscribed to the Google Groups "cp2k" group.
To unsubscribe from this group and stop receiving emails from it, send an email to cp2k+uns...@googlegroups.com.
To view this discussion on the web visit https://groups.google.com/d/msgid/cp2k/784d6269-e613-4a5e-8501-a8e290d9ec99n%40googlegroups.com.

[Nathan Leonard]

Hi Matthias,

Thank you for the suggestion- I just performed an affine transformation in OVITO on a 2x2x2 supercell to make it orthorhombic and exported it to POSCAR. I'll optimize the geometry and then try my run again. :)

Thanks,

Nathan

You received this message because you are subscribed to a topic in the Google Groups "cp2k" group.
To unsubscribe from this topic, visit https://groups.google.com/d/topic/cp2k/QokLzRnmJwk/unsubscribe.
To unsubscribe from this group and all its topics, send an email to cp2k+uns...@googlegroups.com.
To view this discussion on the web visit https://groups.google.com/d/msgid/cp2k/ZRAP278MB0827D56F5D47BB111480F7E8F4EDA%40ZRAP278MB0827.CHEP278.PROD.OUTLOOK.COM.

[Nathan Leonard]

Hi Matthias, I adjusted the structure to be orthorhombic but I am still getting the same error. I have attached the input, xyz and output. Do you have any other suggestions?

Thanks,

Nathan

On Fri, Sep 8, 2023 at 4:35 AM Krack Matthias <matthia...@psi.ch> wrote:

You received this message because you are subscribed to a topic in the Google Groups "cp2k" group.
To unsubscribe from this topic, visit https://groups.google.com/d/topic/cp2k/QokLzRnmJwk/unsubscribe.
To unsubscribe from this group and all its topics, send an email to cp2k+uns...@googlegroups.com.
To view this discussion on the web visit https://groups.google.com/d/msgid/cp2k/ZRAP278MB0827D56F5D47BB111480F7E8F4EDA%40ZRAP278MB0827.CHEP278.PROD.OUTLOOK.COM.

[Anna Hehn]

Hi Nathan,

I also tried what Matthias suggested and I get a non-negative HOMO-LUMO gap, see files attached. 

Best regards,

Anna

To view this discussion on the web visit https://groups.google.com/d/msgid/cp2k/CAE%3DcDnCF_GqfPt2k3YO3bFj8T%3DF2TajecE0gG95eiU6h3sKJ3A%40mail.gmail.com.

[Anna Hehn]

Hi Nathan, 

but I have not checked multiple unit cells and the band gap is very off for PBE, maybe one could try to switch to hybrids (with ADMM) for more accurate band gaps. 

Kind regards,

Anna

[Nathan Leonard]

Hi Anna,

I tried the inputs you gave me and got the same result. Thank you for your help! The band gap value is pretty similar to one I got out of QuantumESPRESSO.

Thanks again,

Nathan

To view this discussion on the web visit https://groups.google.com/d/msgid/cp2k/CACM8JBkAUOrs0ODc84aeNgaUCBw%2BkGez4oUDx18F%2BfKjjqaHkw%40mail.gmail.com.