QuantumATK Forum

QuantumATK => General Questions and Answers => Topic started by: bubble on September 18, 2017, 11:37

Title: How to understand this point in the tutorial?
Post by: bubble on September 18, 2017, 11:37

Hi
In the tutorial
http://docs.quantumwise.com/tutorials/atk_transport_calculations/atk_transport_calculations.html
For the "Check the electrode geometry and size" section, the "Note" indicates that 'The reason for this is that only the nearest-neighbor interactions of the electrode along C are kept in the device calculation (this is necessary in order to describe the electrodes as semi-infinite rather than fully periodic along C).'

Is this point only suitable for the SE method considered here ? Is is suitable for the DFT method? and how to understand it?

It means that the NN interaction along, for example, A or B direction is discarded? I think this will cause incorrect results for the actural devices.

 Thank you!

Title: Re: How to understand this point in the tutorial?
Post by: Ulrik G. Vej-Hansen on September 18, 2017, 13:19

What is meant is not nearest-neighbor atoms, but nearest-neighbor cells, so to speak. So the electrode interacts only with atoms in the electrode extension, and not atoms beyond that. I agree that it is not absolutely clear from the current text, so I will try to make it clearer.

Title: Re: How to understand this point in the tutorial?
Post by: bubble on September 19, 2017, 04:21

Thank you for your reply.

Another question is, what is the expression for the 'spectral current' in the IVcurve section of the tutorial? is it equal to T(E)(fL-fR)? (Here, T(E) transmission spetrum of the given bias, f the fermi function of the L, R electrode)

Title: Re: How to understand this point in the tutorial?
Post by: Petr Khomyakov on September 20, 2017, 10:11

See https://quantumwise.com/forum/index.php?topic=5331.msg23038#new