Dear all,
I am trying to get the band structure of bi layer graphene but I am not quite
sure about the input..I am using experimental values for a and c..Of course a=
2.46 A and c=6.7079 A. Also for bilayer graphene we have 4 atoms per unit
cell..what is confusing me is the distance between the layers within one
bilyaer primitive cell. I read that the distance between one layer and the
other within the bi layer primitive cell is 0.5 c= 3.35 A. this means that the
interaction between the upper layer of one bilayer primitive cell and the lower
layer of the next one is also 0.5c because the whole distance is c.
My question is shouldnt the distance within the same primitive cell be less
than that between one end of a bilayer primitive cell and the other end of the
next one because as far as I know (not sure if I have this as a misconception),
Qunatum Espresso produces images of the main primitive cell and in my case the
next image must be further away so that no interaction would happen between all
layers which would then be a model for graphite. My input for atomic positions
and a and c are as follows:
celldm(1) =4.608737, celldm(3)=2.725459
/
ATOMIC_SPECIES
C 12.00000 C.pz-rrkjus.UPF
ATOMIC_POSITIONS crystal
C 0.000000 0.000000 0.000000
C 0.000000 0.000000 0.500000
C 0.333333 -0.33333 0.000000
C -0.333333 0.33333 0.500000
Hope someone can give me advise or suggestions on this matter.. Thank you
Elie Moujaes
University of Nottingham
NG7 2RD
UK
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