▎ 摘　　要

We derive a general relation between the stacking vector u describing the relative shift of two layers of bilayer graphene and the Chern index. We find C = nu(1 - sign(vertical bar V-AB vertical bar - vertical bar V-BA vertical bar)), where nu is a valley index and vertical bar V-alpha beta vertical bar the absolute value of the u dependent stacking potentials that uniquely determine the interlayer interaction; AA stacking plays no role in the topological character. With this expression we show that while ideal and relaxed minimally twisted bilayer graphene appear so distinct as to be almost different materials, their Chern index maps are, remarkably, identical. The topological physics of this material is thus strongly robust to lattice relaxations.