In this tutorial we will calculate the band structure of Fe.  Start JaTB by typing java –jar JaTB.jar at the system prompt in the directory where you downloaded JaTB.jar.  You should see a periodic table, such as



The color coding follows the nrl convention, in particular the elements whose symbols are in a bold-face type font  have nrl-parameter files and, therefore, can have their electronic properties computed within the nrl-tightbinding approximation.  Click on Fe and you should see the following dialog box



The Info Button provides detailed information about the element you have selected.  The Predefined Button fills in the table with a k-point mesh that has already been defined.  The AddZone Button adds another zone (row) to the table in case you are defining your own k-point mesh.  The Calculate Button begins the calculation once you have finished defining your k-point mesh and the Done Button removes the dialog box.  In this tutorial we will use a predefined k-point mesh, so click on the Predefined Button.  You should see…


Since Iron (Fe) forms BCC crystal the various BCC choices are listed.  Bcc_bandplot is for a band structure calculation with the k-points chosen for a nice looking band plot. The bcc-regular and bcc_special choices are specially chosen to given precise values for the density of states. Select bcc_bandplot and click on the OK Button.



The k-point mesh fills in the table.  Click on the calculate button.  A progressbar widget appears.  When the calculation is done a widget appears with a table of the band energies versus k-value.



Click on the Plot Button to see a band plot.



For most systems there are nine different bands since we are using nine atomic orbitals (1 s, 3 p and 5 d orbitals) in the calculation.  Various ways of viewing this result can be selected from the Menu Items.  Finally, you can save the result to a text file if you wish to use your own graphing program.  Congratulations, you have computed a band structure.