Tutorial

From FEFF

This chapter demonstrates how to do a simple FEFF calculation using the Graphical User Interface (GUI). There are more, varied examples throughout this manual and in the feff90/test directory of your FEFF distribution. However, we recommend you start here. You will first need to install the FEFF code and the GUI. If you have not yet done so, we recommend you look at the installation instructions in the back of this manual. If you have difficulties during the installation, we suggest you first contact your system administrator for help, and, if necessary, one of the FEFF Project contributors.

We start by calculating the X-ray Absorption Spectrum of GeH4. To begin, please open the FEFF-GUI either from the command line or by double-clicking the program icon on your desktop, and proceed below. Note that the GUI is updated regularly, and the screenshots in this manual may be somewhat different from the actual jfeff GUI on your system. Select open from the file menu.

Image:open1.png

Browse to the examples directory and select one of the example `feff.inp' files. The examples directory is located in the directory where you unpacked Jfeff. Eg., it might be `My Documents/feff90/test/GeH4/feff.inp'.

Image:open2.png

After the example data is opened, have a look around. You will see many input options, corresponding to `CARDS' discussed in the next chapter. Many have default values for this simple test calculation. Have a look at the atomic coordinates, and try to see where the type of spectroscopy and the relevant path length cutoff are set. You can look up information on any card in the next chapter and you will also see more information simply by hovering your mouse over a particular field or button. When you have satisfied your curiosity, click the run button to run the example.

Image:run1.png

Wait until feff has finished.

Image:run2.png

Open a new plot frame using the tools menu.

Image:plot1.png

The `xmu.dat' data set for the last opened `feff.inp' file is automatically loaded when the plot frame is opened. Select open from the file menu in the plot frame to open another data set.

Image:plot3.png

Select the original set of data in the example directory.

Image:plot4.png

The recently calculated data set can be hidden using the checkbox on the left.

Image:plot5.png

If your results differ from the provided reference, there may be a problem with your installation that you need to correct before proceeding. If not - Congratulations! You have succesfully finished your first feff9 calculation.




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