Ab-initio analysis of superstructures revealed by STM on bilayer graphene

Abstract

In this work we performed density functional theory calculations for a twisted bilayer graphene (BLG). Several conmensurable rotation angles were analyzed and for each one a constant height mode STM image was obtained. These STM images, calculated under the Tersoff-Hamman theory, reproduce the main features experimentally observed, paticularly superstructures and giant orrugations. In this way we confirm that STM characterization of twisted BLG can produce superstructures whose tunneling current intensity maxima occur over regions with AA stacking. Additionally we give new evidence in favour of an electronic origin for the superstructures instead another physical grounds.