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QuantumATK => General Questions and Answers => Topic started by: Fabrizio on June 11, 2021, 11:35

Title: Transmission Eigenvalue/state does not support transverse electrode repetitions
Post by: Fabrizio on June 11, 2021, 11:35

Dear All,
I built a molecular junction by following the tutorials:

https://docs.quantumatk.com/tutorials/molecular_junction/molecular_junction.html

https://docs.quantumatk.com/tutorials/molecular_device/molecular_device.html

and in particular I used "Mirror" to generate the right electrode from the left one.
Then I performed semiempirical calculations (just to have a preliminary check) with SK, and I succeded in calculating the equilibrium transmission spectrum, device DOS and IV curve.

Nevertheless, in the transmission analyzer, when I analyze transmission in different bias points, there is the message:
" Calculation of eigenstates is not supported for DeviceConfigurations with transverse electrode repetitions. "

and in addition if I try to calculate transmission eigenvalues and eigenstates I get the following error messages:
 
" NL.ComputerScienceUtilities.Exceptions.NLNotImplementedError: TransmissionEigenvalues does not support transverse electrode repetitions. "

" NL.ComputerScienceUtilities.Exceptions.NLNotImplementedError: TransmissionEigenstate does not support transverse electrode repetitions. "

How can I solve this issue?
Is it necessary to build the electrodes in another way (in that case how)?
Is that a limit of SK method or is it a general constraint of the geometry?

I also attach the script.

Thank you all for the attention and the answers,
Kind regards,
Fabrizio.

Title: Re: Transmission Eigenvalue/state does not support transverse electrode repetitions
Post by: Anders Blom on June 16, 2021, 23:19

Yes, you have the right idea, you need to set up the electrodes as supercells, rather than using the automatically detected repetitions (3x in the Y-direction).

If you still have the setup in the Builder, just go back to "Device from Bulk" and choose "Set up electrode cross-section as a supercell"

I would also recommend to add 1 or 2 more gold layer inside the central region, you currently only have an exact copy of the electrode in there, which can cause some problems, esp. if you later want to change the device.

Title: Re: Transmission Eigenvalue/state does not support transverse electrode repetitions
Post by: Fabrizio on June 17, 2021, 16:54

Thank you very much for your kind answer and suggestions, It works fine!

Kind regards,
Fabrizio.