some question about the results' evaluation

[Roc]

Dear everyone,
       
 I have investigated one organic molecule, and calculated the structure and electron properties of the organic molecule in advance by dmol3 package, and found that its HOMO-LUMO gap is about 6eV,
     
 For the two-probe system[Au(111)-organic molecule-Au(111)] , The results such as zero bias transmission spectrum, I-V curve, G-V, and dI/dV-V curve have been posted, as follows,
I am  confused about the results, especially, how to explain the peak of the G-V curve, and I get the zero bias conductance is about 0.0029G0, very small. through analyzing  the results, can I get more informations about the organic molecule. thanks!

[Nordland]

Hey anyipeng.

If the band gap is 6 eV, and molecule does not couple at all to the electrodes, then we would except that the effect of the molecule is not different from that of a vacuum between the electrodes. To some extend, the calculation you show, support this thesis. In figure 2 we see the trends as almost ohmic resistance, however figure 1 and figure 3 reveals that there are more information to be extraced as you said.

If I was you, I would calculate the molecular energy spectrum for the isolated molecule and the calculate the MPSH eigenvalues for the molecule
in this device, then we would gain the knowlegde of determining if the peaks comes from the coupling with the electrode, or it is something else?

[Roc]

Thank you Nordland for your advice. I will try to analyze other properties of the molecule like you said.