For this exercise we will use the EXPGUI interface to access the
features of GSAS.
The method used to start EXPGUI depends on what type of computer you are
using. On Windows, EXPGUI is typically started by clicking on the appropriate
desktop icon, or by selecting an entry in the START menu.
In Unix, it is typically started
by typing the command expgui in a Unix terminal window (it is also possible
to create icons & menu entries in some versions of Unix).
GSAS/EXPGUI Alumina tutorial (part 1)
Creating an Experiment File
In all platforms, once EXPGUI has been started,
a GSAS Experiment (.EXP) file must be selected.
The window shown to the right is opened when EXPGUI is started,
where file to be used is selected.
The .EXP file is the heart of a GSAS project. While other files
are used by GSAS programs, all structural information and control parameters
are contained within this file.
The first step in this tutorial
is to select the directory where the al2o3001.gsa, bt1demo.ins and
alumina.cif files were placed. Do this by clicking
on the "Directory" button at the top of the window, or by navigating
up and down the directory tree by clicking
on the "<Parent>" or individual directory names.
Clicking on the folder icon with an arrow on it
(to the right of the directory button)
has the same effect as the "<Parent>" entry.
Once the correct directory has been located, the next step is to create
a new, empty, .EXP file.
To do this, the file name we wish to use (corundum) is typed into
the bottom box of the file selection window.
Note that the capitalization you use here does not
matter and .EXP is added by default.
After the name has been entered press the "Read" button or
press the keyboard "Enter" key.
To make sure that you really intend to create a new Experiment file,
rather than the more common task of opening a previous file, the
warning message to the right is displayed and you must click on the "Create"
button to continue.
At this point, you are prompted to provide an overall title for the experiment
file. Enter anything you would like (preferably something that will remind
you what you were doing a year from now, when you try to figure out what
this strange file was for. When you have finished entering information, press
the "Set" button.
At this point, the Experiment file, CORUNDUM.EXP, has been created
and EXPGUI displays what (little) information can be found in this file, as is
Note that the title is displayed near the top of the window in a "edit"
box -- this title can be changed simply by typing into the box.
Above the title is the last "history record." GSAS
records a history record each time a program is run that modifies
the .EXP file and this information is displayed here.
In the next step we will start adding information to this experiment file.
Add a phase to the Experiment