[Wien] mbjlda approximation and experimental lattice constant

[f.tran at pci.uzh.ch]

The problem of MBJ is that it is an exchange potential Vx for which there is no associated exchange functional Ex.
In WIEN2k, I arbitrarily chose the LDA exchange functional ExLDA to be associated to the MBJ Vx. It means that
if you do a volume optimization with MBJ, the volume will be close to the LDA value because ExLDA is used.
The MBJ potential should be used only for electronic and magnetic properies, but not geometry optimization.

You can look at this:
http://prb.aps.org/abstract/PRB/v86/i19/e195106

F. Tran

-----"Jameson Maibam" <j.maibam_official at yahoo.com> wrote: -----
To: <f.tran at pci.uzh.ch>, "A Mailing list for WIEN2k users" <wien at zeus.theochem.tuwien.ac.at>
From: "Jameson Maibam" <j.maibam_official at yahoo.com>
Date: 04/22/2013 04:36PM
Subject: Re: Re: [Wien] mbjlda approximation and experimental lattice constant

I have a doubt regarding your meaning of LSDAmBJ potential. In your paper physical review b 85,205108(2012) eq. 1 (mBJ exchange potential) contains a parameter c, which is invesely propotional to square root of Vcell: the unit cell volume. Which means it is related to lattice constant.
Would you please clear my doubt.

Regards
Dr. J. Maibam

------Original message------
From: <f.tran at pci.uzh.ch>
To: "A Mailing list for WIEN2k users" <wien at zeus.theochem.tuwien.ac.at>
Date: Monday, April 22, 2013 8:48:40 AM GMT+0200
Subject: Re: [Wien] mbjlda approximation and experimental lattice constant

MBJLDA is only a potential not an energy functional, therefore there is no "MBJLDA lattice constant".
Choose either the lattice constant obtained from a standard functional (LDA or GGA) or from experiment.

F. Tran

-----wien-bounces at zeus.theochem.tuwien.ac.at wrote: -----
To: "wien at zeus.theochem.tuwien.ac.at" <wien at zeus.theochem.tuwien.ac.at>
From: Sahra Sahraii 
Sent by: wien-bounces at zeus.theochem.tuwien.ac.at
Date: 04/21/2013 09:23PM
Subject: [Wien] mbjlda approximation and experimental lattice constant

  
Dear WIEN2k experts  
I want to use the mbjlda approximation to obtain the band structure of a semiconductor compound, but I don’t know how I can choose the lattice constant. when I studied some articles about this compound, I found that the experimental lattice constant is chosen when the mbjlda approximation is used, Is it a force ( using the experimental lattice constant during the mbjlda approximation) or I can obtain the optimized lattice constant and then calculate the band structure using this lattice constant?


Best Regards


 sahra sahraii
   
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