[Wien] Dependence of DOS on Emin and Emax

[Peter Blaha]

1) How many k-points did you use for the DOS ?

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.

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

4) I don't quite understand you int file. Why do you analyse d- and 
f-electrons for H ??? And why do you have no "tot" value ?
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 ?

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
--------------------------------------------------------------------------
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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