File input and output from NanoLanguage scripts can be handled in a number of different ways depending on what you want to do. If you want to store information for visualization in Virtual NanoLab, you would want to use a VNL file. If you wish to save your calculation for later analysis in ATK, you should use a so-called checkpoint file (stored in the NetCDF format). Furthermore, you also have the option of printing your results in a nicely formatted form by using nlPrint(); this allows for easy plotting using third-part software like Gnuplot. Alternatively, you could also just rely on the standard I/O methods of Python to save, e.g., band structures, energy spectra, or even whole 3D grids. For more information on the various options, please refer to the examples in the tutorial sections of the manual.

The functions listed below, which are used to control reading and writing data to and from VNL files, formatted printing, as well as reading data from NetCDF files, are imported by including one (or both) of the following module import statements in your script:

from ATK.KohnSham import *
from ATK.TwoProbe import *

Furthermore, the following functions are used to control the creation of the checkpoint files, and the amount of information printed by the program when running calculations:

Each is imported via the main ATK package by using the following import statement:

from ATK import *