Quantum interference comparison between benzene, naphthalene, and azulene single molecular junction.

The ability to build devices from single-molecular junctions depends on the fabrication of molecular structures. Here we report significant changes in the transmission coefficient for different connectivities for polycyclic aromatic hydrocarbons (PAHs). In this study, we are using density functional theory DFT compared with the single orbital tight binding TB to investigate the transmission coefficient for three different molecules which are benzene, naphthalene, and azulene with different point connections with electrodes. In the case of benzene the para connection, are leads to constructive quantum interference CQI, and the meta link to distractive quantum interference DQI. Subsequently, azulene and naphthalene have an equal number of atoms, with five different connections, the result shows the even-even or odd-odd connection is DQI while the even-odd connection is CQI. This result is supported by the wave function molecular orbital plot. Finally, the TB calculations are in good agreement with DFT.Keywords: PAHs, DFT, Quantum interference, Tight binding, Transmission coefficient.