Hi,
When I add graphene from database and I repeat A and B to make a large size, is it the same result like Brillouin Zone folding?
Yes, repeating the cell along A and B will result in a folding of the phonon bands in the Brillouin zone.
What I want to do is the phonon dispersion graphene on a substrate as function of different interface bonding.
If I make an interface between graphene and a substrate, I can't repeat its structure to obtain phonon dispersion.
Am I right?For a repeated structure, you will still obtain a phonon dispersion, but the bands will be folded, hence the analysis might be complicated.
For a 1x1 structure, the analysis of the phonon band structure of graphene on a substrate is simpler, see Nano Lett. 10, 4335 (2010)
http://pubs.acs.org/doi/abs/10.1021/nl101657vHow can I have phonon dispersion without BZ folding with many atoms?
In a repeated structure, you will still get the correct band dispersion, but the phonon bands will be folded and difficult to analyze.
If you want to unfold the phonon bands of the supercell and map them into those of a 1x1 unit cell, unfortunately this is not possible at the moment in VNL.
Regards,
Daniele.