Theoretical investigation of the band structure of picene single crystals within the GW approximation

We investigate the band dispersion and related electronic properties of picene single crystals within the GW approximation for the electronic self-energy. The width of the upper highest occupied molecular orbital (HOMOu) band along the Γ–Y direction, corresponding to the b crystal axis in real space along which the molecules are stacked, is determined to be 0.60 eV and thus 0.11 eV larger than the value obtained from density-functional theory. As in our recent study of rubrene using the same methodology [S. Yanagisawa, Y. Morikawa, and A. Schindlmayr, Phys. Rev. B 88, 115438 (2013)], this increase in the bandwidth is due to the strong variation of the GW self-energy correction across the Brillouin zone, which in turn reflects the increasing hybridization of the HOMOu states of neighboring picene molecules from Γ to Y. In contrast, the width of the lower HOMO (HOMOl) band along Γ–Y remains almost unchanged, consistent with the fact that the HOMOl(Γ) and HOMOl(Y) states exhibit the same degree of hybridization, so that the nodal structure of the wave functions and the matrix elements of the self-energy correction are very similar.