Exploring the charge density distribution and the electrical characteristics of Oligo phenylene ethylene molecular nanowire using quantum chemical and charge density analysis

Abstract

To understand the charge density distribution and the electrical characteristics of Au and thiol substituted Oligo phenylene ethylene (OPE) molecular nanowire, a quantum chemical calculation has 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. The applied electric field (0.05–0.26VÅ−1) altered the geometrical conformation, charge density distribution and the electronic energy levels of molecular wire. The bond topological analysis characterizes the terminal AuS, SC bonds as well as the bonds of central OPE molecule for zero and the applied fields. The field polarizes the molecule, in consequence of that the dipole moment of the molecule abruptly increases from 3.23 to 39.73D. For the zero bias, the HOMO–LUMO gap is 2.17eV, as the field increases this gap rapidly decreases to 0.4eV; presumably, this small energy gap at higher field may enhance the conductivity. The I–V characteristics of the molecule have been studied for various applied fields.