Comparative ab initio and DFT study of neutral aniline oligomers

Abstract

The geometric and electronic structures of neutral aniline oligomers were investigated using comparative ab initio restricted Hartree-Fock (RHF) and density functional theory (DFT) calculations to model polyaniline in different oxidation states. The various base forms of polyaniline were leucoemeraldine (LM) trimer, pernigraniline (PNA) trimer and an emeraldine (EM) pentamer. The DFT calculations carried out in Becke-Lee-Yang-Parr (BLYP) functionals reproduced the approximately 4.0 eV π-π* transition of LM base and the approximately 2.0 eV Peierls gap transition of PNA base. However, RHF method predicted large discrepancies with experimental measurements.