Replies : 4 Last Post : July 06, 2016 (Wed) 09:26:46

70

BaO

Posted on : July 05, 2016 (Tue) 23:47:15

by Von Braun Nascimento

Dear Prof. Akai,

I am trying to get some results on BaO rocksalt structure.
My lattice parameter value is quite good when compared to the experimental value.
However, my band structure calculation is not correct. It does not look like reference results and there are bands crossing the Fermi level.
I am trying to replicate the rocksalt structure by using two fcc lattices, one for Ba and other for O.
Please help me with this issue. My input file follows below this message.

Thanks in advance,


c---------------------BaO----------------------------------
go data/bao_akai
c------------------------------------------------------------
c brvtyp a c/a b/a alpha beta gamma
fcc 10.4621, 1.0000, 1.0000, 90.0000, 90.0000, 90.0000,
c------------------------------------------------------------
c edelt ewidth reltyp sdftyp magtyp record
0.001 1.0 nrl ev nmag init
c------------------------------------------------------------
c outtyp bzqlty maxitr pmix
update 8 250 0.03
c------------------------------------------------------------
c ntyp
2
c------------------------------------------------------------
c type ncmp rmt field mxl anclr conc
Ba 1 0 0.0 2 56 100
O 1 0 0.0 2 8 100
c------------------------------------------------------------
c natm
4
c------------------------------------------------------------
c atmicx atmtyp
0 0 0 Ba
0.5 0.5 0.5 O
c------------------------------------------------------------

 
 

78

[Re:04] BaO

Posted on : July 27, 2016 (Wed) 09:31:26

by Administrator

Dear Von Braun Nascimento,

I do not quite understand your question. I tried your input and I have gotten a band gap of around 1.5eV. Although the fermi level is pinned at the bottom of the valence band, the system obviously is an insulator with a big band gap (density of state at the Fermi level will diminish if you use smaller edelt). The reason why the Fermi level is not located at the centre of the band gap is the following (if it is your question): There is no way to fix the position of the Fermi lever at T=0K, i.e. the Fermi level is not defined because it is an insulator. Also the chemical potential is not well defined since the calculation is for T=0K.

 
 

77

[Re:03] BaO

Posted on : July 27, 2016 (Wed) 01:28:42

by Von Braun Nascimento

Dear Profs. Akai and H. Gomi,

I made the suggested modifications but my BaO is still metallic.
There are states at the Fermi level.

Thanks in advance, Von

My input file :

c---------------------BaO----------------------------------
dos data/baoakai_dos
c------------------------------------------------------------
c brvtyp a c/a b/a alpha beta gamma
fcc 10.6140, , , , , ,
c------------------------------------------------------------
c edelt ewidth reltyp sdftyp magtyp record
0.001 2.0 nrl ev nmag 2nd
c------------------------------------------------------------
c outtyp bzqlty maxitr pmix
update 4 250 0.03
c------------------------------------------------------------
c ntyp
2
c------------------------------------------------------------
c type ncmp rmt field mxl anclr conc
Ba 1 0 0.0 2 56 100
O 1 0 0.0 2 8 100
c------------------------------------------------------------
c natm
2
c------------------------------------------------------------
c atmicx atmtyp
0 0 0 Ba
0.5 0.5 0.5 O
c------------------------------------------------------------

 

74

[Re:02] BaO

Posted on : July 07, 2016 (Thu) 02:15:22

by Hitoshi GOMI

Additionally, in case of dos calculation, record should be 2nd.
Is it ok?

c---------------------BaO----------------------------------
dos data/bao_akai
c------------------------------------------------------------
c brvtyp a c/a b/a alpha beta gamma
fcc 10.4621, , , , , ,
c------------------------------------------------------------
c edelt ewidth reltyp sdftyp magtyp record
0.001 2.0 nrl ev nmag 2nd
c------------------------------------------------------------
c outtyp bzqlty maxitr pmix
update 8 250 0.03
c------------------------------------------------------------
c ntyp
2
c------------------------------------------------------------
c type ncmp rmt field mxl anclr conc
Ba 1 0 0.0 2 56 100
O 1 0 0.0 2 8 100
c------------------------------------------------------------
c natm
2
c------------------------------------------------------------
c atmicx atmtyp
0.0 0.0 0.0 Ba
0.5 0.5 0.5 O
c------------------------------------------------------------

 
 

71

[Re:01] BaO

Posted on : July 06, 2016 (Wed) 09:26:46

by Hitoshi GOMI

Hello Von Braun Nascimento,

I think the ewidth is too small.
(And natm should be 2.)
Please try the following input.

c---------------------BaO----------------------------------
go data/bao_akai
c------------------------------------------------------------
c brvtyp a c/a b/a alpha beta gamma
fcc 10.4621, , , , , ,
c------------------------------------------------------------
c edelt ewidth reltyp sdftyp magtyp record
0.001 1.5 nrl ev nmag init
c------------------------------------------------------------
c outtyp bzqlty maxitr pmix
update 4 250 0.03
c------------------------------------------------------------
c ntyp
2
c------------------------------------------------------------
c type ncmp rmt field mxl anclr conc
Ba 1 0 0.0 2 56 100
O 1 0 0.0 2 8 100
c------------------------------------------------------------
c natm
2
c------------------------------------------------------------
c atmicx atmtyp
0.0 0.0 0.0 Ba
0.5 0.5 0.5 O
c------------------------------------------------------------

 
 

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