▎ 摘　　要

The electronic structures of 30 degrees twisted double bilayer graphene, which loses the translational symmetry due to the incommensurate twist angle, are studied by means of the tight-binding approximation. We demonstrate the interlayer decoupling across the 30 degrees twisted interface in the vicinity of the Fermi level from various electronic properties, including the density of states, effective band structure, optical conductivity, and Landau-level spectrum. However, at Q points, the interlayer coupling results in the appearance of new Van Hove singularities in the density of states, new peaks in the optical conductivity and, importantly, the 12-fold-symmetry-like electronic states. The k-space tight-binding method is adopted to explain this phenomenon. The electronic states at Q points show charge distribution patterns more complex than the 30 degrees twisted bilayer graphene due to the symmetry decrease. These phenomena also appear in the graphene monolayer on the AB-stacked graphene bilayer with a 30 degrees twist angle.