 |
 |
|
| Geometry for transport calculations | Further analysis of the results |
| |
|
|
| Geometry for transport calculations | Further analysis of the results |
Table of Contents
In this chapter you will learn how to perform a transport calculation, once the device geometry has been defined.
Send the device geometry you just constructed
in the previous chapter
to the Script Generator by using the "Send to" icon
in the lower right-hand corner of the Builder.
The Script Generator should open up and display the device geometry.
To set up the calculation of the transmission spectrum
double-click New
Calculator 
in the "Blocks" panel to add it to the script panel,
double-click the Analysis-icon
and
select TransmissionSpectrum from the menu, and finally
change the output file name to li-h2.nc.
To modify the parameters of the calculator, double-click New Calculator in the "Script" panel.
To speed up the calculation, change the Density mesh cut-off to 50 Hartree.
Click OK to close the dialog.
Now double-click TransmissionSpectrum in the "Script" panel.
Adjust the energy range to [-2, 5] eV, and change the self-energy calculator to Krylov (the fastest method).
Again, click OK.
The script is now ready to be run. It is however good practice to
always save the input script for future reference, so first choose
File → Save as... from the menu and save the generated Python script
under a suitable name, like li-h2.py.
Send the script to the Job Manager by pressing the
“Send to” button
in the lower right-hand corner of the Script Generator,
and select Job Manager.
Click Run Queue to start the calculation. A window appears with log messages about how the calculation procedes. The job should finish in a couple of minutes only. You can save the log output for future reference by pressing Ctrl+S in the log window.
You have now performed a complete transport calculation with ATK! Granted, it was only for zero bias, and you have yet to analyze the results, but the fundamental work flow is the same for all transport calculations as for this system.
In order to visualize the results of the calculation you just performed, go through the following steps:
Locate and select the file li-h2.nc in the VNL main window.
Select the Transmission spectrum in the list of objects in the file, shown in the Result Browser (the upper right panel).
Click Show next to the "Plot" command in the Result Viewer (the lower right panel).
A plot of the transmission spectrum will now appear. You can right-click the plot and choose "Anti aliasing" for improved plot quality.
By right-clicking on the window the plot can be saved by
choosing Export image from the contex menu.
The data contained in the plot can also be exported for use
in a third-party plotting software by choosing Export data.
Do not close the Script Generator, as you will reuse it in the next section.
| |
|
|
| Geometry for transport calculations |
|
Further analysis of the results |