[Wien] Dependence of DOS on Emin and Emax
wh at fysik.cn
wh at fysik.cn
Fri May 22 15:26:19 CEST 2020
Dear Prof. Blaha,
Thank you so much for the detailed explanations.
I got the DOS for all 128 atoms by switching to G broadening. It is indeed a key parameter for my system, as which is metallic and also contains short H-H distances around 1 Angst.
Best regards,
Hui
Hui Wang
School of Physics & Electronic Engineering
Harbin Normal University
Shida Street No. 1 Harbin
From: Peter Blaha
Date: 2020-05-22 14:43
To: wien
Subject: Re: [Wien] Dependence of DOS on Emin and Emax
1) How many k-points did you use for the DOS ?
I use a 216 k-points (almost 6x6x6 K-mesh) for a ~6.7x6.8x6.7 Angst.^3 cell.
2) In large supercells it can be that bands are extremely narrow. This
means the the DOS as calculated with the tetrahedron method (this works
"bandwise") may consist of a series of "delta functions", and since you
calculate the DOS on a certain E-grid, it might be that for one grid you
have those nearly-delta-peaks on an E-grid point, for the next one you
don't.
Thanks for you clear explanation.
If you have "only delta-functions" (condensed H2 at ambient conditions),
you may have to switch to G and /or L broadening in case.int (this
should not be necessary for H at extremely high pressures).
3) I suggest you copy also the case.outputt files and check there: the
band ranges (WIEN2k calculates only the DOS for complete bands (for band
#xxx all k-points must have at least xxx eigenvalues).
check the DOS but also the integrated DOS. If it happens that at a
particular energy the integrated DOS increases, but the DOS is zero, you
have hit such a "delta-peak".
Often it helps, if you decrease the delta-E in case.int
The integrated DOS looks OK now.
4) I don't quite understand you int file. Why do you analyse d- and
f-electrons for H ???
The DOS of d and f should be zero for hydrogen. I export them by the code only for post-processing convenience.
And why do you have no "tot" value ?
I calculate the DOS-tot in another run for post-processing convenience.
You know that the s-DOS contains only the contribution inside the atomic
sphere and this will be only a small fraction of the total DOS for your
H example. (check out the renormalized DOS option in the pes program).
The s-DOS at EF will be a meaningless and quite arbitrary number.
And finally: plot the DOS ! How does it look like ?
Thanks, I will check out the remornalized DOS after I understand the related parameters.
On 5/22/20 2:56 AM, wh at fysik.cn wrote:
> Dear W2k users,
>
> I'm running W2k_19.2 to calculate the DOS of condensed hydrogen with 128
> H atoms in a P1 structure. I was stucked in the last step, i.e. x tetra:
> The DOS of different H atoms comes out for different combinations of
> Emin and Emax.
> For example,
> ** Emin=-0.4 and Emax=0.4** EF=0.37400, d.1 means dos for H1
> [iron at ilogin x0.4]$ grep ' 0.37400 ' d.1
> 0.37400 0.24467672 0.02124318 0.00146735 0.00000000
> [iron at ilogin x0.4]$ grep ' 0.37400 ' d.2
> 0.37400 0.32811075 0.03422544 0.00159283 0.00000000
> [iron at ilogin x0.4]$ grep ' 0.37400 ' d.3
> 0.37400 0.00000000 0.00000000 0.00000000 0.00000000
> [iron at ilogin x0.4]$ grep ' 0.37400 ' d.4
> 0.37400 0.20743760 0.02327048 0.00102359 0.00000000
> [iron at ilogin x0.4]$ grep ' 0.37400 ' d.5
> 0.37400 0.23075266 0.02746148 0.00144383 0.00000000
>
> ** Emin=-0.5 and Emax=0.5** EF=0.37400, d.1 means dos for H1
> [iron at ilogin x0.4]$ cd ../x0.5/
> [iron at ilogin x0.5]$ grep ' 0.37400 ' d.1
> 0.37400 0.00000000 0.00000000 0.00000000 0.00000000
> [iron at ilogin x0.5]$ grep ' 0.37400 ' d.2
> 0.37400 0.32811043 0.03422542 0.00159283 0.00000000
> [iron at ilogin x0.5]$ grep ' 0.37400 ' d.3
> 0.37400 0.30522904 0.01708757 0.00128918 0.00000000
> [iron at ilogin x0.5]$ grep ' 0.37400 ' d.4
> 0.37400 0.00000000 0.00000000 0.00000000 0.00000000
> [iron at ilogin x0.5]$ grep ' 0.37400 ' d.5
> 0.37400 0.00000000 0.00000000 0.00000000 0.00000000
>
> I got almost the same results in both runs for H2. However, '0.00000000
> 0.00000000 0.00000000 0.00000000' comes for H3 in the first
> case, and which changes to H1, H4 and H5 in the second.
>
> How can I get the DOS of all 128 atoms in one run?
>
> I run x tetra for each H atom using the following shell script,
> #
> for ((i=1; i<=128; ++i))
> do
> cp i$i.int case.int
> sed '2d' -i case.int
> sed '2 i\ -0.4 0.002 0.4 0.003\ ' -i case.int
> x tetra
> mv case.dos1 d.$i
> kill -9 tetra
> done
> mkdir x0.4
> mv d.* x0.4
>
> The i$i.int file were generated by the folloring scpript,
> #
> for ((i=1; i<=128; ++i))
> do
> configure_int_lapw -b $i s,p,d,f end
> mv case.int i$i.int
> done
>
> Taking H1 for example, the case.int is as following,
> 1 #Title
> -999.00000 0.002 .8744325353 0.003 #Emin, DE, Emax, Gauss-Broad
> 4 N 0.000 #Number of DOS-cases,G/L/B broadening (Ry)
> 1 2 s-H
> 1 3 p-H
> 1 7 d-H
> 1 13 f-H
> SUM: 0 2 # NUMBER OF SUMMATIONS, max-nr-of summands
> 2 5 # this sums dos-cases 2+5 from the input above
>
> Thanks,
> Hui
>
> ------------------------------------------------------------------------
> Hui Wang
> School of Physics & Electronic Engineering
> Harbin Normal University
> Shida Street No. 1 Harbin
>
>
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--
P.Blaha
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Peter BLAHA, Inst.f. Materials Chemistry, TU Vienna, A-1060 Vienna
Phone: +43-1-58801-165300 FAX: +43-1-58801-165982
Email: blaha at theochem.tuwien.ac.at WIEN2k: http://www.wien2k.at
WWW: http://www.imc.tuwien.ac.at/TC_Blaha
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