ABSTRACT
The electronic properties and Coulomb excitations of the lower-symmetry trilayer AAB are, respectively, explored by the tight-binding model and the modified random-phase approximation in detail. The former characteristics have been identified from scanning tunneling spectroscopy measurements. It is also noticed that most of the pristine-layered graphenes exhibit semimetallic behaviors, for example, the AAA, ABA, and ABC stacking, and the bilayer twisted and sliding systems. The lower-symmetry AAB stacking is predicted to have more complicated magneto-optical absorption spectra. The low-lying energy bands of the trilayer AAB stacking, which principally originate from the 2pz orbitals, is calculated with the tight-binding model. They are almost consistent with those using the first-principles method. The unusual energy dispersions create two kinds of van Hove singularities in trilayer AAB stacking. The asymmetric square-root peaks and the shoulder structures, respectively, arise from the constant-energy contours and the band-edge states of the parabolic dispersions.
