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

[rsaha at icredd.hokudai.ac.jp]

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