A major theoretical challenge of studying twisted transition metal dichalcogenide (TMD) bilayers is that the unit cell of such structures is very large and therefore difficult to address using first-principles methods. However, twisted TMD bilayers form moir\'e patterns, which consist of regions of commensurate stacking, either smoothly interpolated into one another or separated by sharp domain walls. In this paper, we study twisted TMD bilayers by studying the properties of the constituent commensurate structures. Using density functional theory (DFT), we compute band structures for commensurately-stacked MoS2/WS2 and MoSe2/WSe2 bilayers in both 0∘ and 60∘ orientations, and we highlight variations in band structures across different commensurate geometries. These band structure variations arise from diverse factors such as metal atom asymmetry between layers (Mo vs. W), differences in interlayer hybridization, and Brillouin zone alignment. We comment on the consequences of such band structure differences for optical experiments and on the effects of strain on moir\'e pattern electronic structure.
@article{arxiv.1909.02495,
title = {Commensurate structures in twisted transition metal dichalcogenide heterobilayers},
author = {Madeleine Phillips and C. Stephen Hellberg},
journal= {arXiv preprint arXiv:1909.02495},
year = {2019}
}