AB INITIO AND DENSITY FUNCTIONAL STUDIES OF POLYTHIOPHENE ENERGY BAND GAP

ABSTRACT – The energy band gap of intrinsic thiophene monomer and dimer were calculated using Hartree-Fock (HF) and density functional theory (DFT) methods employing various combinations of exchange and correlation functionals with electron core potential (ECP) split valence basis sets. HF overestimates band gap by up to 6.10 eV for thiophene monomers and dimers. DFT calculations with hybrid functionals (B3LYP and B3P86) give an excellent results (4.06 eV and 4.11 eV) which are in good agreement with the experimental energy band gap (4.05 eV)