QuantumATK Forum

QuantumATK => General Questions and Answers => Topic started by: mano on October 15, 2015, 07:53

Title: Left density matrix - Temperature
Post by: mano on October 15, 2015, 07:53

Hello,
              In the "The non-equilibrium Green's function (NEGF) method" (https://www.quantumwise.com/documents/manuals/ATK-12.8/ReferenceManual/index.html/chap.negf.html), the left density matrix (also right) is calculated using "electron temperature T_L".   

I have following two questions regarding it.

1) Which of the following is used "electron Temperature" or "Electrode temperature" (mentioned in the input script) ?

2) If Electrode temperature  (mentioned in the input script) is used then while plotting IV characteristics what is the role of mentioning Electrode temperature of Left or Right?

With regards,
Mano

Title: Re: Left density matrix - Temperature
Post by: Umberto Martinez on October 15, 2015, 08:27

You define electron_temperature in the LCAOcalculator in numerical accuracy parameters:
http://www.quantumwise.com/documents/manuals/latest/ReferenceManual/index.html/ref.numericalaccuracyparameters.html
This is used to define the Fermi distribution of the electrons during the SCF calcualtion.

Electrode temperature is used to calculate the current from the transmission spectrum analysis:
http://www.quantumwise.com/documents/manuals/latest/ReferenceManual/index.html/ref.transmissionspectrum.html
this is also used to determine the Fermi distributions of the electrons in left and right electrodes, according to the formulas reported in the link.

Title: Re: Left density matrix - Temperature
Post by: mano on October 15, 2015, 15:32

Thank you  very much for your kind and immediate reply.

I hope that I understood correctly your explanation, ie., for the calculation of left and right density matrix, electrodes temperature is used. If I am wrong then please correct me. If this is the case then again mentioning different Electrode temperature of Left or Right electrodes in IV plotting is misleading. Could you explain it?

Title: Re: Left density matrix - Temperature
Post by: Umberto Martinez on October 16, 2015, 09:41

electron_temperature is used for the density matrix and you defin it in NumericalAccuracyParameters, please go through the links mentioned.

the IV curve is calculated from the different  transmission spectra, as reported in the transmisisonspectrum entry in the reference manual.

Title: Re: Left density matrix - Temperature
Post by: mano on October 17, 2015, 00:56

Thank you very much for this clarification.