Why I cannot find the pathway in the right part of the device?

[lknife]

Dear expert,

After the IV curve calculation of a in-plane interface based device, I wanted to have a look at the pathway under a specific bias. However, although it showed the pathway in the left part of the device, there is no pathway in the right part. I cannot understand it since in my view, the two-probe device is just like a “Serial circuit“, the current flow along the route should be equal. The current in this case is 3.64 nA (0.15V), not very low.

Why I cannot find the pathway in the right part of the device? Can anyone here help me with this problem?

Attached are three files related to this problem:
1. the transmission spectrum under bias 0.15V;
2. the .py file for the post-calculation  from the transmission spectrum;
3. the result of the second step: the pathway

[Anders Blom]

You should turn off the bonds when plotting pathways, since the pathways are drawn between atoms and so the bonds will obscure them. If the transmission is very low you may need to lower the threshold - by default very small atom-atom transmission values for the pathways are hidden to not clutter the picture.

[lknife]

Thank you for your kind reply! After I turned off the bond and lowered the threshold to a very low value (1e-9), the pathway is like the picture attached. I saw some lines in the right part of the device, but very faint, far less the magnitude of those in the left part. The closer to the right electrode, the fainter the lines are.

What I want to know are: why the magnitude of the pathway along the transport direction is much different on the two sides of the interface? Did many of the electrodes be reflected by the interface? Where did the current in the transmission spectrum come from, the electrodes flow that passed through the interface and successfully got to the right electrode?

Another question: what do the "Angle" and "weight" of the color mode in the setting dialog of "transmission pathway" refer to?

Hoping to get your kind help again!

[Anders Blom]

By default this object shows the electrons are coming from the left and scatter/tunnel towards the right. So if the transmission is low, and it is in the case you showed, a very small part of the electrons make it into the right electrode, hence the vanishing arrows. You can also compute the electrons going right-to-left by setting the keyword "contributions" to Right.

The color mode just tells you how the arrows should be colored: based on the angle the pathway makes with the Z axis, or the magnitude of the transmission.

[lknife]

Thank you very much for your reply! I am not sure if the transmission is low since the current is 3.64nA. If the current was come from the electrons reached the right electrode, maybe the faint lines in the right part of the device just represented the electron flow (3.64nA).

[lknife]

Dear Anders Blom,

As you said,  "You can also compute the electrons going right-to-left by setting the keyword "contributions" to Right", I have just done that. The result is attached here. It looks the same as the one calculated using "contributions-left".

The bias applied on the device is (0.15V, 0V). Since the device is a diode-like device, the effect of the bias (0, 0.15V) is not the contrary of that with bias (0.15V, 0V). 

If the gradually fainter lines represented that the current flow reduced gradually because of scattering or something others when the electrons went from the left electrode to the right electrode (contribution-left),   when I set "contribution-right" and got the same result, what did the lines in the pathway mean? They are getting stronger from right to left. I cannot imagine that more and more electrons were involved into the current as the current flowed from right to left electrode.

I am a little confusing with the concept "contribution-left" and "contribution-right". Hoping to get your kind help! Thank you very much!

[lknife]

What's the "scaling power" in the "transmission pathway" plugin in the viewer? I found when I reduced the threshold, I can change the thickness of the lines on the pathway by adjusting the "scaling power", the lower the "scaling power" is, the thicker the line are. Now I can get a clearer image of the pathway, seen the attached image of the same result of the pathway.
 

[Anders Blom]

The tooltips of each setting will tell you how they affect the plot