why the transimission peak corresponding to a localized state

[zhangguangping]

Dear everyone:
 
I have now encountered a result which I can not understand well. Please help me to explain it.
 
I have put the result in the attachment. The solid line is the transmission spectrum of the molecular junction (Au/molecule/Au system), the dash line is the projected density of state to the bare molecule and the down-triangle is the MPSH for bare molecule+6Au (which are the nearest neighboring Au atoms to acount for the interaction between molecule and the surface electrodes.)
 
As seen, there are two sharp PDOS  peaks locating at 0.3 and 1.0 eV and two broad PDOS peaks at 0.2 and 1.4 eV. The MPSH for the two sharp PDOS peaks are very localized and the two broad PDOS peaks are delocalized which can be understood. But the transmission at 0.3 and 1.0 eV are 0.74 and 0.73 respectively, which are noticeable. To my knowledge, a localized PDOS should has a very small transmission. Do I have a wrong understand? Or is there something else I misunderstand? And In what case, the localized PDOS can have a noticeable transmission?
 
Please help. Any explanation is appreciated.
 
Best regards.
 
Yours,
 
Guangping

[nori]

But the transmission at 0.3 and 1.0 eV are 0.74 and 0.73 respectively, which are noticeable.

These look like a Fano resonance which is derived from hybrid between continuum states (= delocalized states) and bound states (= localized states).
So I guess your calculation result is reasonable physically.

To my knowledge, a localized PDOS should has a very small transmission.

Bound states have no transmission coefficient.
So if a very localized state is just a bound state, your thought is right.

[zhangguangping]

Dear nori,

Thanks for your explanation very much. I also guess they are Fano resonance. The case at 0.3 eV is can be understand easily because the localized PDOS (bound state) superposes on the very broad PDOS (continuum state, the delocalized molecular state is broaded in a wide energy range). This accords with the condition of the  Fano resonance. However, the sharp PDOS at 1.0 eV separate away from the delocalized PDOS at 1.3 eV. So I doubt whether the second belongs to Fano resonance?

Thanks again very much for your kind reply.

Yours,

Guangping

[nori]

However, the sharp PDOS at 1.0 eV separate away from the delocalized PDOS at 1.3 eV.

Indeed it's subtle but I interpreted that the delocalized PDOS at 1.3 eV seems to have a long tail and would interact with the sharp PDOS at 1.0 eV.
Of course my interpretation might be wrong, so you should investigate the physical properties of your system more carefully.

[zhangguangping]

Dear nori,

Thanks very much for your detailed and kind reply.

Best

Yours,

Guangping

[arunkumarcr]

Hello,

I was looking at the transmission and fano-resonance found.

Is it possible to get the phase-angle Vs energy as specified in the diagrams of the following paper..?

'Effect of quasi-bound states on coherent electron transport in twisted nanowires' Phys. Rev. B 83, 245439 (2011)

Regards
arun