Theoretical investigation on conformational behavior of 2,2′-bithiophene under the influence of external electric field at ab initio levels

The potential energy surface of 2,2′-bithiophene under the influence of the external electric field (EF) constructed by point charges has been fully investigated with various basis sets at Hartree-Fork and density functional theory levels. After comprehensive comparison among these basis sets, 6-31G and higher split-valence basis sets with polarization function and diffuse function are considered to be suitable in the calculations. Then, we show the evolutions of the molecular geometry and the electronic structure under the influence of the external EF. Considering the interaction between EF and molecular dipole moment, quantitative relationships between several molecular properties and the EF strength have been presented and interpreted, which may facilitate the design of molecular device.