In order to get a deeper insight into the interference phenomenon, we have performed non-equilibrium Green’s function calculations using the ground-state electron density (of the molecules in gas phase) obtained from the density functional theory. In Figure 4, the calculated transmissions through the π-systems of both molecules are shown. At energies between the HOMO and LUMO levels, the transmission of the meta-OPV3 molecule is more than an order of magnitude smaller than that of a para-OPV3, with an anti-resonance occurring at 4.56 eV, where the transmission drops

substantially. This drop is Entospletinib clinical trial caused by the destructive interference between transmission coefficients of different selleck screening library orbitals. In the Landauer formalism, the charge propagation through molecules can be described as a transmission through different molecular orbitals [7]. Using the non-equilibrium Green’s function formalism, it is possible to separate the total transmission into contributions from the individual molecular orbitals. Since these contributions are complex (i.e., they have an amplitude and a phase), interference effects can arise when transmission through different orbitals are combined. Figure 4 Calculated transmissions through the π-systems Momelotinib clinical trial of both molecules. (a) Calculated transmission of para- and meta-OPV3 derivatives in gas phase. (b) Amplitude and phase of the

transmission through the HOMO and LUMO of a para-OPV3 molecule. (c) Amplitude and phase of the transmission through the HOMO and LUMO of a meta-OPV3 molecule. The amplitudes of the transmissions are approximately the same for both molecules, however, the phase of the

transmission through the LUMO differs by π from para- to meta-OPV3, while the phase selleck chemical of the HOMO is the same (see Figure 4b,c). This results in constructive interference for a para-OPV3 molecule when the transmission through the HOMO and LUMO are combined. For meta-OPV3 molecule, the phase shift results in destructive interference between the HOMO and LUMO transmission, as evident from the drop in the full transmission plot (Figure 4a). It should be noted that also the HOMO-1 and LUMO+1 orbitals contribute to the transmission within the HOMO-LUMO gap. The phase behavior of these orbitals is the same as for the HOMO and LUMO, i.e., constructive and destructive interference for para- and meta-OPV3 molecules, respectively. Note that the transmission of the meta-OPV3 does not go to zero at the anti-resonance due to the contributions from the HOMO-2 and HOMO-3 orbitals. This analysis therefore confirms the occurrence of constructive and destructive interferences in the molecules studied experimentally. Conclusion In conclusion, we have shown that the low-bias conductance through a single meta-OPV3 molecule is one order of magnitude smaller that through a para-OPV3 one.