Structural, Electronic, and Optical Properties of Bulk Graphdiyne

Graphdiyne is a newly discovered 2D carbon allotrope with many special features. Using density functional theory plus van der Waals (vdW) density functional, we investigate the structural, electronic, and optical properties of several possible graphdiyne bulk structures. We find that bulk graphdiyne can be either a semiconductor or a metal, depending on its stacking configuration. The interlayer vdW force red shifts the optical absorption peaks of bulk graphdiyne relative to those of the monolayer, and spectra of different stackings display notable differences in the energy range below 1 eV. Finally, combining with previous electrical and optical experiments, we identify the structure of the recently synthesized graphdiyne film.