[DFTB-Plus-User] Help required: Helical boundary condition

[Ben Hourahine]

Hello Ranajit,

there is an old script for repeating helical structures, which is posted at

https://gist.github.com/bhourahine/5c0bddab24687ed8902b82c5fdb744d7

to repeat a helical geometry, unlike the dp_tools scripts, you need to
edit the gen file to add the repeats at the end of the file. For example
for the C nanotube with a 10 fold rotation axis:

   2  H
  C
    1 1    0.2756230044E+01    0.2849950460E+01    0.1794011798E+01
    2 1    0.2656226397E+01    0.2949964389E+01    0.3569110265E+00
    0 0 0
    0.2140932670E+01 18.0 10
2 9

where the repeats count from 0 (i.e. C convention). The script does not
understand shifts in the origins.

The number of k-points along the translational direction often needs to
be quite large to converge these structures.

Regards

Ben



On 23/03/2021 07:34, rsaha at icredd.hokudai.ac.jp wrote:
> CAUTION: This email originated outside the University. Check before clicking links or attachments.
>
> Hello all Users,
> I am new to the DFTB+ world.
> Recently, I want to run some calculations using the helical boundary
> condition.
> I went through the manual and internet to find information about it. But
> there is not much with the helical boundary condition under DFTB+.
> I have tried "repeatgen" to check the input but it did not work.
> I want to know how to check the inut geometry, let's say for 5
> repeatative unit (as we check for 1D, 2D or 3D structure using repeatgen)
>
> It will be helpful, if any one can share and/or suggest how to do
> calculations with helical boundary condition. What precauions I should
> conider.
> Thank you in advance.
> Regards
> Ranajit
>
>
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-- 
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            SUPA, Department  of  Physics,
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