About MPSH

[yangzw1985]

I have carried out the MPSH calculation of two probe model.But the HOMO-LUMO level are too narrow.what is the reason? Can anyone tell me how to recognize the results?Thanks in advance!

[Anders Blom]

I suppose the system is metallic in the central region.

[yangzw1985]

Hi, it is a ZnO semiconductor nanowire in the central region.I can not explain the results.In my knowledge, the band gap for semiconductor should be 0.2-3.5eV.Can you explain it?

In my first calculation, the results includes molecule atoms and surface atoms. Now I have calculate the MPSH with only projection atoms, and the results are only four values.Attached is the results.

I want to know which one is reasonable. when I calculate the MPSH of my two probe model, the projection Atoms,molecule atoms, surface atoms ,which one should be included?

Thanks.

[Anders Blom]

Nanowires are often semiconducting, but the smaller they get the more metallic they become. Thus the wires people typically measure on are almost always semiconducting, but for narrower diameter tubes you should really compute the band structure to see how it looks.

The MPSH concept is designed for molecules between metal surface, put simply. Therefore it doesn't really make sense in your case, unless there is a specific impurity for instance, then you can project onto that atom (and it's neighbors, typically).

[Nordland]

The surface of a ZnO wires is metallic, and hence it will not generate nice clear MPSH states as the surface states couples strongly with the metallic electrodes.

5 years ago, when I was conducting optical experiments on ZnO nanowires, I had many problem with the surface being metallic. I was trying to optical measure the carrier confinement in the nanowires as they became smaller. However there were a secondary trend namely that the optical spectra was more and more determined by the surfaces states, and hence the wire started acting like a conductor and absorbed all the fine structure of the electronic properties.

[yangzw1985]

Thank you for your reply!