(color online) Phase diagrams of the Kitaev tubes composed of even (a) and odd number (b) of chains, which belongs to class D. t_x is chosen as energy unit. Δ x = 0.8 , t y = 0.5 , and Δ y = 0.6 . The integer numbers in panels (a) represent 0,1,2 index, while those in panel (b) represent the Z 2 index.