Hi,

Did you use mBJ to calculate the band gap in both procedures?

FT

On Thursday 2018-02-08 09:35, Dr. K. C. Bhamu wrote:

Date: Thu, 8 Feb 2018 09:35:08
From: Dr. K. C. Bhamu <kcbham...@gmail.com>
Reply-To: A Mailing list for WIEN2k users <wien@zeus.theochem.tuwien.ac.at>
To: A Mailing list for WIEN2k users <Wien@zeus.theochem.tuwien.ac.at>
Subject: [Wien] a note on lattice parameter optimization

Hello,

Using experimental lattice parameters(a Ang), I optimized the structure with 
two options.

1. Directly optimized the structure without min_lapw ... and the optimized 
lattice parameters are in the vicinity of Exp a (~0.01 Ang accuracy) and the 
calculated band gap (from mBJ2) is in agreement with reported value ~0.3 eV 
less.

2. First relaxed the structure and then optimized this relaxed structure 
(without min_lapw ....). In this case the optimized lattice parameters are 
reduced by ~0.05 Ang and the band gap vanished or largely reduced.


Why is the second way of doing band structure not working?

I tested it on many systems. In some case system became metal and in some cases 
band gap largely reduced when  I used the fully relaxed structure for 
optimization.


Thanks,


Bhamu





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