[Wien] Born effective charge calculation

[Rubel, Oleg]

To add to the discussion, here is a tutorial "Born effective charge of GaN" from the last WIEN2k workshop (http://susi.theochem.tuwien.ac.at/events/ws2019/Exercises_19-tot.pdf). In this case LDA performs very well. One can try to do TBmBJ to see a difference.

Some systems with a small Eg (for example InN) have Eg = 0 at LDA/GGA level, which created a problem for Berry phase calculations that need a gap. In this case TBmBJ (or DFT+U) would be your best option.

I hope it will help
Oleg

--
Oleg Rubel (PhD, PEng)
Department of Materials Science and Engineering
McMaster University
JHE 359, 1280 Main Street West, Hamilton, Ontario L8S 4L8, Canada
Email: rubelo at mcmaster.ca
Tel: +1-905-525-9140, ext. 24094
Web: http://olegrubel.mcmaster

________________________________________
From: Wien <wien-bounces at zeus.theochem.tuwien.ac.at> on behalf of Laurence Marks <laurence.marks at gmail.com>
Sent: Saturday, September 5, 2020 22:39
To: A Mailing list for WIEN2k users
Subject: Re: [Wien] Born effective charge calculation

>From what I have found and my tests, either -eece or +U are better as GGA's overestimate. MBJ does not appear to be better. However, values are often not that well measured experimentally.

---
Prof Laurence Marks
"Research is to see what everyone else has seen, and to think what nobody else has thought", Albert Szent-Gyorgi
www.numis.northwestern.edu<http://www.numis.northwestern.edu>

On Sat, Sep 5, 2020, 19:09 Wien2k User <wien2k.user at gmail.com<mailto:wien2k.user at gmail.com>> wrote:
Dear Wien2k users,

Is it more precise to use mBJ for the calculation of born effective charge or gga is sufficient? (in a case where there is no comparison values)
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