small clarifications about electrodes

[medeepak]

hi

i had created this structure (removed a couple of layers of carbon atoms and used passivate script) but now i am not able to attach electrodes to it

it shows an error "Total width of electrodes may not exceed width of central region"
can you please what is this error about and how to rectify this. i want to attach electrodes to the same structure. i have faced this error a lot times before as well and i dont know when exactly this comes as sometimes i am able to attach electrodes to constricted GNRs

regards
deepak

[kstokbro]

The error message is misleading and we will change that.

The problem is that your central region structure, does not include enough of the electrode, and VNL can therefore not recognize what part of the structure is the electrode.
When you prepare your central region you must have ~7 Å of the electrodes in the central region, in order for ATK to recognize the electrode part.

[Anders Blom]

Which version are you using? In 11.2.3 (the latest), if you click the "Device" icon in the Builder with your file loaded you get a more helpful error message, that no valid set of electrode can be found. As Kurt wrote, you need to include the electrodes in the central part already. I assume you have created the system by having a full-width ribbon (as wide as it is close to the edges in Z) and then you removed a row top/bottom and added hydrogens. That's fine, you should just leave a bit more of the full-width system at the edges (2-3 periods), then all will work much better.

See http://quantumwise.com/publications/tutorials/mini-tutorials/99 for important details on this.