Reduction of ring-torsion angles and band gap of polyaniline under high pressure

Variation ground states of pernigraniline-base polymer were investigated with various values of potential parameter V2,0 in an extended Ginder-Epstein model. The results showed that ring-torsion angles and the energy gap reduced with decreasing V2,0. We estimated pressure perpendicular to nitrogen plane of a chain in the polymer by the ring-torsion angles. While V2,0 decreased from 2.0 to 0.8 eV, our estimated pressure increased from 0 to 9.03 GPa. The results agree with the experimental observations that electrical conductivity is increasing with applied pressure until a saturated value.