No convergence during LMD state calculation for ZnO doped with TM.

Posted on : February 05, 2019 (Tue) 01:08:55

by Mohammad Saidur Rahman

Hello Administrator/akaikkr Users,

I want to calculate the Curie Temperature for ZnO (zinc blend structure) doped with TM such as Ti. I shall give you the INPUT file that I used at the end of my comment.
So here's what I've done step by step as follows.

1. I have first performed the "go" calculation for pure ZnO (no doping).

2. Then I have created the potential file for ZnO doped with Ti, using "fmg" executable app. Here's the data that I have used to create potential:

../data/ZnO 1 2 3 4
../data/ZnO_doped 1 2 2 3 4

3. Then I have performed the "go" calculation for ZnO doped with Ti.
4. After that I have created another potential file for LMD state calculation of ZnO doped with Ti, using "fmg". Here's the data that I have used to create new potential:

../data/ZnO_doped 1 2 2 3 4
../data/ZnO_doped_lmd 1 2 -2 2 -2 3 4

4. Finally, I have the potential to start LMD state calculation for ZnO doped with Ti. I performed the calculation but no convergence during self consistent iteration.

Here's my input file for ZnO (no doping):

c----------------------ZnO----------------------------------
go data/ZnO
c------------------------------------------------------------
c brvtyp a c/a b/a alpha beta gamma
fcc 8.719 , , , , , ,
c------------------------------------------------------------
c edelt ewidth reltyp sdftyp magtyp record
0.001 1.2 sra mjw mag 2nd
c------------------------------------------------------------
c outtyp bzqlty maxitr pmix
update 4 400 0.035
c------------------------------------------------------------
c ntyp
4
c------------------------------------------------------------
c type ncmp rmt field mxl anclr conc
O 1 1 0.0 2 8 100
Zn 1 1 0.0 2 30 100
Vc1 1 1 0.0 0 0 100
Vc2 1 1 0.0 0 0 100
c------------------------------------------------------------
c natm
4
c------------------------------------------------------------
c atmicx atmtyp
0 0 0 O
0.25 0.25 0.25 Zn
0.5 0.5 0.5 Vc1
0.75 0.75 0.75 Vc2
c------------------------------------------------------------

Input file with doping:

c----------------------ZnO_doped----------------------------------
go data/ZnO_doped
c------------------------------------------------------------
c brvtyp a c/a b/a alpha beta gamma
fcc 8.719 , , , , , ,
c------------------------------------------------------------
c edelt ewidth reltyp sdftyp magtyp record
0.001 1.2 sra mjw mag 2nd
c------------------------------------------------------------
c outtyp bzqlty maxitr pmix
update 4 400 0.035
c------------------------------------------------------------
c ntyp
4
c------------------------------------------------------------
c type ncmp rmt field mxl anclr conc
O 1 1 0.0 2 8 100
Zn 2 1 0.0 2 30 92
22 8
Vc1 1 1 0.0 0 0 100
Vc2 1 1 0.0 0 0 100
c------------------------------------------------------------
c natm
4
c------------------------------------------------------------
c atmicx atmtyp
0 0 0 O
0.25 0.25 0.25 Zn
0.5 0.5 0.5 Vc1
0.75 0.75 0.75 Vc2
c------------------------------------------------------------

Input file for LMD state of doped ZnO:

c----------------------ZnO----------------------------------
go data/ZnO_doped_lmd
c------------------------------------------------------------
c brvtyp a c/a b/a alpha beta gamma
fcc 8.719 , , , , , ,
c------------------------------------------------------------
c edelt ewidth reltyp sdftyp magtyp record
0.001 1.2 sra mjw mag 2nd
c------------------------------------------------------------
c outtyp bzqlty maxitr pmix
update 4 400 0.035
c------------------------------------------------------------
c ntyp
4
c------------------------------------------------------------
c type ncmp rmt field mxl anclr conc
O 1 1 0.0 2 8 100
Zn 4 1 0.0 2 30 46
30 46
22 4
22 4
Vc1 1 1 0.0 0 0 100
Vc2 1 1 0.0 0 0 100
c------------------------------------------------------------
c natm
4
c------------------------------------------------------------
c atmicx atmtyp
0 0 0 O
0.25 0.25 0.25 Zn
0.5 0.5 0.5 Vc1
0.75 0.75 0.75 Vc2
c------------------------------------------------------------

Do you think my above procedure was correct?
How can the "no convergence" problem be resolved?
Another problem occurred when I tried to use ewidth= 1.5 for ZnO with doping. The following message appeared during self consistent iteration:

"***msg in cstate...corelevel near ebtm found for nclr= 8
**"

And without doping (for pure ZnO), 1.5 works fine.

When I used ewidth=1.2. It didn't show the above warning statement. Does ewidth play any role for convergence during iteration?

If you could help me with the above issues by answering or suggesting your valuable insights, I'd tremendously be benefited.

Thanks in advance.

-Mohammad Saidur Rahman