ARTEMIS - Interpretation of the FEFF calculation
This page provides a concise overview of the Feff calculation. At the top of the page is a summary of some of the statistics of the calculation. Below that is a chart showing the details of each path from the calculation. For each path, the degeneracy, the half path length and the amplitude factor are shown. The last column shows a tokenized summary of the scattering path -- this allows you to see at a glance which atoms were involved in the path.
The information and context menus available on this page allow you organize, understand, and manipulate the paths in this Feff calculation. Pretty much all functions involving the paths except writing math expressions for the path parameters are available on this page.
The colors and fonts used in the chart convey information:
There are interesting and useful context menus on every part of this page. These menus are available by right clicking.
Right clicking anywhere in the text box at the top of the page will pop up a menu with options for viewing files from the Feff calculation.
Right clicking in the interpretation chart will post a menu of options relevant to the path on the line on which you clicked. Each of the four kinds of paths given by the four fonts described above has its own menu.
For paths that are imported in the fit, the menu offers options for plotting the path, displaying that path's page, including or excluding the path in the fit, selecting or deselecting that path for plotting, making that path the default for evaluation of def parameters after a fit, displaying the text of the file containing the path, or discarding the path. The choices for including or excluding and for selecting or deselecting depend on the state of that path in the Data and Paths List. Also some options might be greyed out depending on the state of that path.
For paths that have not been imported into the project, the context menu allows you to import the path with the option of displaying its page or leaving the display on the Feff interpretation. For paths that are unavailable for import, a message saying so is posted when one of those lines is right-clicked.
The interpretation chart allows for extended selection of lines in the chart. You can select additional paths by holding the control key while clicking with the left mouse button. Holding the shift key while left clicking selects all line between the anchor (the one outlined with a dashed line) and the one you click on. You can also click and drag to select all the lines you drag over. When more than one line is selected, the content of the context menu change to reflect functionality that makes sense for many paths. Extended selection in the interpretation chart is therefore a good way of including/excluding, selecting/deselecting, or plotting a large number of paths.
The context menu that pops up when many lines are selected may be a little surprising. Its contents depend upon the state of the anchored line, which in this case is the one that you right-click on to post the menu. The options in the context menu will be suitable to the state of the anchored selection regardless of the states of the other selected lines. If you choose a menu item that does not make sense for some of the selected lines, those lines will be ignored.
Here is a concrete example. Suppose that you select a number of lines, some of which are included in the fit and some of which have not been imported in the fit. If you then right click on one of the included paths, you will get options appropriate to included paths. If you then ask to plot the selected paths along with the data, the included paths will be plotted and the imported paths will be ignored. If, instead, you click on one of the paths that has not been imported yet, the context menu will give you the option of importing the selected paths. In that case, the paths that have already been imported will be ignored.
On occassion you might see that lines in the Feff interpretation
do not properly report on the contents of the path. When this
happens, site tags are replaced by this string: <?>. There
are a couple common reasons you might see the <?> tags:
files.dat or paths.dat files then rerunning the last module to
produce specialized output.
You have discovered a bug in the algorithm Artemis uses to harvest
information from the Feff calculation. IN that case, you should
send the feff.inp file or the Artemis project file to Bruce so
he can fix the problem.
Note that the appearance of the <?> tags is probably not an
indication that Feff has misbehaved. The Feff calculation has
to run to completion and generate its normal output before this
problem can manifest itself. The Feff calculation is almost
certainly usable to analyze the data. The Feff interpretation page
is Artemis's attempt to organize information about the Feff
calculation in some user-friendly format. That this organizational
effort failed is not necessarily an indication that Feff failed.