[Wien] Supercell

[Khuong P. Ong]

Dear Prof. Peter Blaha and Georg,

  Many thanks for your help. Section 10.4 in new Wien2k userguide is really 
useful. It helped me a lot.

  I have one more question: how big is the number of k-points for super cell?

The UG said that supercells require less k-points than the original small 
cell. But how much is it?

Let suppose that in order to calculate precisely electronic structure of 
one material we need 200 k-points. Now if we generate a super cell: 2x2x1, 
3x3x1, 4x4x1. Approximately how many k-points do we need?

  In case of small cell we can estimate this number of k-point by following 
instruction in textbook " DFT and the family of..." by Dr Stefaan 
Cottenier. But in case of big cell I'm afraid that I'm not able to proceed 
such instruction. That is because one SCF- cycle takes some hours or even 
more.

  Please advice me how to estimate number of k-points wisely.

  I'm grateful so much for helps.

Regards,
Khuong
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