A Charge Density Analysis on Quarter Thiophene Molecular Nanowire Under Applied Electric Field: A Theoretical Study

Abstract

A Quantum chemical calculation and charge density analysis on gold and thiol substituted quarter thiophene molecular nanowire have been carried out using high level Density Functional Theory (DFT) with the basis set LANL2DZ coupled with the Bader’s theory of atoms in molecules to understand its charge density and energy density distributions for the zero and various applied electric fields. The applied electric field (0.03–0.13 V A −1 ) altered the geometrical conformation, charge density distribution and the electronic energy levels of molecular wire. The bond topological analysis performed for zero and various applied electric fields characterizes, the terminal Au S, S Ca s well as the central bonds of the quarter thiophene molecule. The field highly polarizes the molecule and this effect increases the dipole moment of the molecule from 2.69 to 13 D. For the zero bias, the HOMO–LUMO gap is 1.713 eV, as the field increases this gap rapidly decreases to 1.172 eV. The electrostatic potential maps for various applied electric field shows the charge accumulated regions of the molecule. The I–V characteristics of the molecule have been studied against various applied fields.