File Name : ap_1.png Caption : comparison of the band structures for two possible stackings (rotational angle=21.8o). (a) abab and (b)abba. the rotation axis goes through atoms aa of layers 1 and 3 in the abab case and through aa atoms of layers 1 and 4 in the abba case. (c) band structures calculated with a tb model in both cases. the inset shows differences at high energies. File Name : tbsimple2.pdf Caption : (a-c) band structures calculated with a tb model including only one intralayer term (γ0), one direct interlayer hopping (γ1) between ab-stacked graphene and an exponential decay hopping between atoms in the inner twisted layers.there is no gap with this model for large angles. in d we show two calculations of the bands of dtbg with a rotation angle of 2.0o. dashed red lines: the outer bernal layers are uncoupled to the inner ones; continuous blue lines: outerbernal-stacked layers coupled with a 1/10 fraction of γ1. notice that the size of the gap in the coupled case is exactly the shift of the dirac cone of the twisted layers.