The calculation of conductance.

[Yu Hailin]

Dear all, the follow method to calculate the conductance  for two-electrode system is reasonable?

The method include:
i. calculate the transmission spectrum at zero bias.
ii. using the calculated transmission spectrum to calculate the conductance at different electrode_voltages, such as:

conductance = TransmissionSpectrum.conductance(electrode_voltages=[0,0.1]*Volt)
print conductance

conductance = TransmissionSpectrum.conductance(electrode_voltages=[0,0.2]*Volt)
print conductance

......

Or it is necessially to calculate the transmission spectrum at different bias before calcualte the conductance?

Thanks in advance!

[zh]

To get more accurate results, you had better do the calculation of transmission spectrum for each bias voltage. More detailed information can be referred to here:
http://quantumwise.com/documents/manuals/latest/ReferenceManual/XHTML/ref.transmissionspectrum.html

[Anders Blom]

As ZH says, if you do not recalculate self-consistently you will not get as accurate results. As the manual says (http://quantumwise.com/documents/manuals/latest/ReferenceManual/XHTML/ref.transmissionspectrum.html), if you give voltages to the conductance method, it will use them and compute the conductance using the zero-bias (or whatever bias used to compute the transmission spectrum) instead of the actual transmission spectrum at the desired bias.

So, it's a quick and dirty approximation to the real calculation, and if the transmission does not depend strongly on the bias (often it does, however), the results are rather good (but there is no guarantee).

Btw, the same approach is available for the current.