[DFTB-Plus-User] Dear DFTB plus users. I am trying to construct the SK parameter file by myself. But i can understand some part.

[Peter Yen]

Dear DFTB users:
I am trying to construct a SK parameter file for gold. Pekka Koskinen had
published a gold paper and i am using the data he fitted for gold to
construct the SK parameter file which i wish can be used in DFTB+. However,
there are some parts i don't fully understand and i think it is not
mentioned in the "Format of the V1.0 slater koster files" documents. I wish
someone could give me suggestions.


I use the simple format for construction

Here are the questions

1.  Line 1  gridDist nGrdPoints
     What is the unit for gridDist?  Is it angstrom or atomic unit?

2. Line 4~4+nGridpoints-1:
    The document mentions that in  this block , the distance will be
increased one "gridDist" unit between each line. I would like to ask is the
distance for line4 refering to "0" ? Or does it  refering to R_0? (R_0 is
1.85*covalent radius i assume.)Because the the distance in Pekka's
parameter file refering  to  0. However, according to the documents, it
seems that in DFTB sk files, it refers to starting R_0. Would anyone
clarify this part for me? And if indeed starting from R_0. How to know this
value for gold used in DFTB+?

3.Spline block
   line4 to 4+nInt-2, what is the unit for nInt? Is it angstrom or atomic
unit?

4. This is the some part extracted from from mio-1-1/C-C.skf

     1 0.02, 500 ,2

      2 0.0    -0.19435511 -0.50489172, -0.0439, 0.341975   0.387425 ,
0.3647 0.0 2.0 2.0

       3 12.01, 19*0.0
      4 20*1.0,
      5 20*1.0,
      6 20*1.0,
      7 20*1.0,
      8 20*1.0,
      9 20*1.0,
     10 20*1.0,
     11 20*1.0,
     12 20*1.0,
     13 20*1.0,
     14 20*1.0,
     15 20*1.0,
     16 20*1.0,
     17 20*1.0,
     18 20*1.0,
     19 20*1.0,
     20 20*1.0,
     21 20*1.0,
     22 20*1.0,

   i dont understand from line4 to line22, can someone explain to me? I
thought it was the H and S matrix elements but it seems not because the
total nGridpoints is 500 ( from line 23 to line 522) and it seems the block
of H and S matrix elements don't include line4 to line22. Can anyone tell
me the purpose of line 3 to line22 ?



Thank you for your help.



With Best Regards

 Peter




-- 
Research Assistant,Physics
Department,NCU,Taiwan
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