Towards first-principles based modeling of poly-3-alkylthiophenes: The nature of interactions in 2,2′-bithiophene dimer

► Interaction energy decomposition is performed for 2,2′-bithiophene dimer using DFT-SAPT. ► Directionality of interactions is studied in wide range of conformational space. ► At equilibrium intermonomer distance simple exchange-dispersion potential is adequate.