Dear Dedi, That would be up to you to decide. The usual choice for graphene is that one site corresponds to one atom, therefore the distances are expressed in unit of the distance between atoms (0.246 nm I think).. Please, try plotting the system you constructed. Best regards, Xavier Le 5 nov. 2015 à 00:49, Dedi Setiabudidaya a écrit :

Dear Sir/ Madam,

I use the codes below to build my graphene system. Could you tell me what is the unit of L and W (or x and y) ? . . . L = 8.0 W = 6.0 def rectangle(pos): x, y = pos return -L < x < L and -W < y < W def lead_shape(pos): x, y = pos return -W/4.0 < y < W/4.0 . . . Thank you in advance.

Best Regards,

Dedi