[Wien] PBE vs mBJ

[Fecher, Gerhard]

This question is just not scientific sound.

You choose the functional and this functional gives you some answer on the electronic structure,
this answer is not the universal answer, it is just that what you asked the computer to do.
Remember that the A in LDA, etc. means approximation !

It is bad habit to change the functional until one finds an answer that one likes to have.

By the way, is your "experimental value" correct at all ?
Did you ask where the gap is comming from in the same way as you ask about the calculation ? 

Ciao
Gerhard

DEEP THOUGHT in D. Adams; Hitchhikers Guide to the Galaxy:
"I think the problem, to be quite honest with you,
is that you have never actually known what the question is."

====================================
Dr. Gerhard H. Fecher
Institut of Inorganic and Analytical Chemistry
Johannes Gutenberg - University
55099 Mainz
and
Max Planck Institute for Chemical Physics of Solids
01187 Dresden
________________________________________
Von: Wien [wien-bounces at zeus.theochem.tuwien.ac.at] im Auftrag von fatima DFT [fatimadft5 at gmail.com]
Gesendet: Sonntag, 30. Juli 2017 15:24
An: A Mailing list for WIEN2k users
Betreff: Re: [Wien] PBE vs mBJ

In addition to this query: For thermoelectric properties, Should we consider LDA/GGA/PBE/../ or can use mBJ if mBJ gives band gap in the vicinity of experimental value?


On Fri, Jul 21, 2017 at 8:28 PM, <tran at theochem.tuwien.ac.at<mailto:tran at theochem.tuwien.ac.at>> wrote:
Hi,

mBJ was made to be good for band gaps only, such that there is
no reason to expect better results than PBE for other properties
like EFG. So, in a publication this would justify to consider the EFG
from PBE instead of mBJ.

FT

On Friday 2017-07-21 16:45, Marcelo Barbosa wrote:

Date: Fri, 21 Jul 2017 16:45:21
From: Marcelo Barbosa <marcelo.b.barbosa at gmail.com<mailto:marcelo.b.barbosa at gmail.com>>
Reply-To: A Mailing list for WIEN2k users <wien at zeus.theochem.tuwien.ac.at<mailto:wien at zeus.theochem.tuwien.ac.at>>
To: A Mailing list for WIEN2k users <wien at zeus.theochem.tuwien.ac.at<mailto:wien at zeus.theochem.tuwien.ac.at>>
Subject: [Wien] PBE vs mBJ


Dear Sirs,

I’m interested in simulating the EFG at impurity sites in wide band gap semiconductors and their impact in the density of states.
I’ve been using the PBE functional to optimize the structure but then I used to mBJ potential to get a better band gap and density of states.
However, the EFG values change considerably from PBE to mBJ, being the PBE results the ones closer to the experimental values.
Therefore, I would like to ask if I can consider the EFG values from PBE and the density of states from mBJ or if this is not a good approach.

Thank you very much.

Best regards,
Marcelo

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