QuantumATK Forum

QuantumATK => General Questions and Answers => Topic started by: karn on November 26, 2014, 12:32

Title: Transmission Spectrum
Post by: karn on November 26, 2014, 12:32

Hi

i want to calculate transmission spectrum at different biases for a two terminal device in one go. is it possible and if yes then how?

Title: Re: Transmission Spectrum
Post by: Umberto Martinez on November 27, 2014, 12:51

yes of course. You can:

- use the IVCurve analysis in the Scripter to do everything in one go.
You will have access to the two transmission spectra from the IVCurve object.
see for example http://quantumwise.com/publications/tutorials/item/820-ni-silicide-si-interfaces#h7-1-iv-curves

- run something like this:

Code

device_configuration =...
calculator = ...

for bias in [0, 0.1, 0.2]*Volt:
    device_configuration.setCalculator(calculator(electrode_voltages=(0,bias)),initial_state=initial_state)
    nlprint(device_configuration)
    device_configuration.update()
    nlsave("filename.nc", device_configuration)    
    initial_state = device_configuration

    # -------------------------------------------------------------
    # Transmission spectrum
    # -------------------------------------------------------------
    transmission_spectrum = TransmissionSpectrum(
        configuration=device_configuration,
        energies=numpy.linspace(-2,2,101)*eV,
        kpoints=MonkhorstPackGrid(21,21),
        energy_zero_parameter=AverageFermiLevel,
        infinitesimal=1e-06*eV,
        self_energy_calculator=RecursionSelfEnergy(),
        )
    nlsave("filename.nc", transmission_spectrum)
    nlprint(transmission_spectrum)

Title: Re: Transmission Spectrum
Post by: karn on November 28, 2014, 07:13

Thanks for your reply. Yeah, i know how to carry out IV curve analysis at different biases and there by clicking on Add more plots i can see dI/dV and transmission spectra. But what i actually meant was that if i could just calculate transmission spectra at different biases without being forced to carry out computationally intensive and time consuming IV curve analysis? i just want to see the transmission spectra at different biases without spending much time. Hope this makes sense.

Title: Re: Transmission Spectrum
Post by: Umberto Martinez on November 28, 2014, 07:53

The time consuming part is the calculation of the transmission spectra. The calculation of the current is done from the TS and takes... nothing.
see the current method here (http://www.quantumwise.com/documents/manuals/latest/ReferenceManual/index.html/ref.transmissionspectrum.html).
Also, if you select the IVCurve object you will see on the right side of the LabFloor a Transmission Analyzer plugin that allows you to analyze in more details each TS.

Anyway, feel free to run the second solution I proposed :)

Title: Re: Transmission Spectrum
Post by: karn on November 28, 2014, 09:50

Let me see if i get this right. You are basically saying that it doesn't matter as far as time consumption is concerned whether we calculate IV curve or just transmission spectra at different biases. Is that what you mean? And yeah, Thanks again for your time.