questions regarding to tutorial of Isotope impurity effect on a single-wall carb

[Jenny]

Hello, everyone.

I've done as the tutorial suggested. However, I'got the different results from the tutorial.
I noticed that the default electrode length here I got is different from the tutorial. And I've tried to build a device with cnt(6,0) without optimization. The electrode length seems match the numbers in the tutorial. However, the resultant transmission spectrum is still different from that in the tutorial. I don't know why. Can somebody help me with it?
And I've attached the script and its result here.


Thank you.

[Jenny]

And the transmission spectrum for the device with isotope C14 ring is attached here.

[Jess Wellendorff]

Dear Jenny.

The tutorial does not say, but you need to manually add a few lines in the script if using ATK 13.8.
You can see below how I have defined parameters for the dynamical matrix calculation. Those parameters should be passed on to the calculator:

# -------------------------------------------------------------
# Calculator
# -------------------------------------------------------------

dynamical_matrix_parameters = DynamicalMatrixParameters(
    atomic_displacement=0.01*Angstrom,
    repeats=Automatic,
    acoustic_sum_rule=False,
    symmetrize=True,
    )

calculator = TersoffCalculator(parameters=Tersoff_C_2010(),
                                                              dynamical_matrix_parameters=dynamical_matrix_parameters,
                                                              )
########################

Then your calculation should work.

[Jenny]

Dear Jenny.

The tutorial does not say, but you need to manually add a few lines in the script if using ATK 13.8.
You can see below how I have defined parameters for the dynamical matrix calculation. Those parameters should be passed on to the calculator:

# -------------------------------------------------------------
# Calculator
# -------------------------------------------------------------

dynamical_matrix_parameters = DynamicalMatrixParameters(
    atomic_displacement=0.01*Angstrom,
    repeats=Automatic,
    acoustic_sum_rule=False,
    symmetrize=True,
    )

calculator = TersoffCalculator(parameters=Tersoff_C_2010(),
                                                              dynamical_matrix_parameters=dynamical_matrix_parameters,
                                                              )
########################

Then your calculation should work.

Thank you, Jess Wellendorff.

It seems work well now. I have another question is that, if I'd like to use this method to calculate my own device, which might consist of two elements(eg: C and Si). So, I need to build the specific potential for that by myself or to refer to others, right? If I'd like to build it on my own. Where can I find the parameters needed as suggested in the tutorial below? Is there something like a library? Thanks again.
https://www.quantumwise.com/publications/tutorials/item/848-adding-combining-and-modifying-classical-potentials

Jenny

[Julian Schneider]

We have quite a lot of predefined potentials for SiC. You can simply use one of those. Send your SiC configuration to the ScriptGenerator, add a New Calculator, double-click it to open its settings, and select ATK-Classical, a list of possible potentials will be available. I'd recommend you use one of the Tersoff potentials, e.g. Tersoff_SiC_2005 or Tersoff_SiC_1989.

[Jenny]

We have quite a lot of predefined potentials for SiC. You can simply use one of those. Send your SiC configuration to the ScriptGenerator, add a New Calculator, double-click it to open its settings, and select ATK-Classical, a list of possible potentials will be available. I'd recommend you use one of the Tersoff potentials, e.g. Tersoff_SiC_2005 or Tersoff_SiC_1989.

I got this. Thank you.
What if I'd like to study about C and metal(eg: C+Al)?  I found there were no available potentials can be used under ATK-Classical. Btw, I'm using atk-13.8.1 version.

Thanks again in advance.

Jenny

[Anders Blom]

13.8 has very few classical potentials - the situation is very different in 2014 and even better in 2015.