The optical properties in the periodic chain and periodic monomer case were calculated with the linearized augmented plane waves plus local orbitals (LAPW+LO) based code exciting. First, azobenezene units were put in a periodic box of a dimension a = 20 Å, b = 20 Å and c = 3.5 Å or c = 8 Å for the periodic chain and monomer case, respectively (Fig. ). The DFT ground state calculations were performed with the PBE functional by sampling the Brillouin zone with a homogeneous 1 × 1 × 4 Monkhorst-Pack k-point grid for the chain and a Γ point calculation for the monomer case. Muffin tin orbitals with radii of 0.8 bohr for H, 1.2 bohr for C and 1.2 bohr for N have been used with |G + k| max of 3.5 and |G| of 14 including 100 empty states for the ground state properties. Quasiparticle (QP) energies were calculated in the G 0 W 0 approximation including 100 empty states in the confined space of 10 occupied and 10 unoccupied states.