[Wien] Electronic Structure of CoP3

[Osama Yassin]

Dear Khan

I faced a similar problem when working on CoSb2, and could solve the
problem by following the instructions given by P. Blaha in an earlier mail.
Just do non-shifted k-mesh scf. Read the comment given below (highlighted
by red colour)..

Osama
---------------------------------------------------------------------------------------------------

You missed an important comment:

CoSb3.scf::GAP  :    0.0502 Ry =     0.683 eV   (provided you have a proper
k-mesh)

PROVIDED YOU HAVE A PROPER K-MESH.
We discussed this several time in the mailing list. If you do the scf-cycle
with a shifted k-mesh and the gap is at gamma, the reported gap in the
scf-file (or the DOS) is NOT ok. (How should it know that the gap at gamma
is smaller, when gamma is not calculated ??)

*You can get a "correct" gap using an unshifted (but denser) k-mesh, or you
read the* gap value from the band structure.


Am 12.07.2013 08:54, schrieb wien-bounces at zeus.theochem.tuwien.ac.at:
Dear Prof, Blaha and Wien2k users,,

I'm looking for your urgent help about the following:

- I'm calculating DOS and band structure of CoSb3. I noted strange
behaviour when comparing the values obtained from DOS and band structure.
The analysis utility gives me a value of Eg equals to 0.684eV while the
band structure shows crossing of Fermi level at G-point (i.e metallic). If
I shifted manually the value of Eg in case.insp to match the top of the
valence band the band gap appears to be ~ 0.4 eV. These values were
obtained when I used mBJ scheme. I got similar behaviour when using GGA,
but of course the Eg values are smaller.

- I have  doubt about something going wrong after preparing the required
files for the band plot (may be in case.output1). This is because when I
directly plot bands, i.e without - x lapw1 -band -up/-dn steps, I get the
correct band gap. Of course the lines look not connected with no symmetry
points written. However, I'm not sure about what input files I should
provide to you, I attach case.struct, DOS and the cases of the band plots.


Analysis of parameter:
:FER :GAP
in CoSb3.scf (showing last 10 / 1 lines)

--- FER -----------
in  1 files:
CoSb3.scf::FER  : F E R M I - ENERGY(TETRAH.M.)=   0.5239017718
--- GAP -----------
in  1 files:
CoSb3.scf::GAP  :    0.0502 Ry =     0.683 eV   (provided you have a proper
k-mesh)


I attach two files for plots of DOS and band structures


-- 
Osama
Prof Dr Osama Ali Yassin
Professor of Solid State Physics and ICTP regular associate
Department of Physics, Faculty of Science
Taibah University, A-Madinah Al-Munawarh, K. Saudi Arabia


-- 
Peter Blaha
Inst.Materials Chemistry
TU Vienna
Getreidemarkt 9
A-1060 Vienna
Austria
+43-1-5880115671
-- 
Peter Blaha
Inst.Materials Chemistry
TU Vienna
Getreidemarkt 9
A-1060 Vienna
Austria
+43-1-5880115671


On Tue, Dec 31, 2013 at 3:13 PM, Banaras Khan <banarasphysicist at gmail.com>wrote:

> Dear WIEN2k Members
>
> I am working on CoP3 skutterudute compound and tried to get the electronic
> structure by minimizing the internal parameters.
>
> Bandgap is clearly seen in density of states and from the grep command
> but the Bandgap is not there in the Electronic Band
>
> Structure. Please guide me..
>
>    Thanks
>
>    Banaras Khan
>    University of Malakand, Chakdara, Pakistan.
>
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>


-- 
*Osama          *
*Prof Dr Osama Ali Yassin *
*Professor of Solid State Physics and ICTP regular associate*
*Department of Physics, Faculty of Science*
*Taibah University, A-Madinah Al-Munawarh, K. Saudi Arabia *
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