Larch 0.9.53 is now available for download and use. Although the last announcement here was in April for version 0.9.51, there have been several improvements especially to the XAS Viewer application since the last release, mostly in anticipation of upcoming workshops and short courses.
- There are important fixes for reading Spec/Bliss HDF5 files from ESRF - thanks to Mauro Rovezzi for this. You can now import multiple XAS spectra from Spec/HDF5 files.
- XAS Viewer now supports doing Feff6l or Feff8l calculations and has a GUI interface for doing a Feffit fit to a sum of Feff paths. In the current GUI frame, this is limited to analyzing one dataset at a time. This brings up a related feature:
- A database (sqlite3) of CIF structures from the American Mineralogist Crystal Structure Database (
http://rruff.geo.arizona.edu/AMS/amcsd.php) is included. The version of this database in the source code contains about 9000 structures. If your machine is well-connected to the internet and can reach https:/
millenia.cars.aps.anl.gov, a more complete version (~30 Mb) with 20,000 structures will be downloaded and used. To be clear, the 9000 structures in the smaller set are probably sufficient -- what is removed is some CIFs from publications with many similar structures (T or P dependence) or structures so large and complex that they will be hard to make into single Feff files.
- The CIF files from this DB or other CIF files (well, CIF is notoriously variable!) can be automatically converted to Feff input files (using python tools from the Materials Project, modified a bit). Because many of these CIF structures contain fractional occupancy, that is handled (probably poorly, but at least not failing) by randomly selecting atoms based on the site occupancy.
- XAS Viewer has a CIF Browser (from the Feff menu) where you can browse by mineral name, included atoms, etc. From that you can generate a Feff6l or Feff8l input file, potentially edit that input file, and run Feff to generate path files. These will be organized in your home folder (C:\Users\Name\larch\feff for most Windows users, $HOME/.larch/feff for Linux/MacOS). There is also a Feff browser to select Feffnnnn.dat files from your previous Feff runs and bring them into the "Feffit" tab in XAS Viewer to use in the sum of paths fitting of EXAFS spectra.
Of course, all of this Feff and Feff fitting interface should be viewed as "initial release" and comments, suggestions, and bug reports are welcome. The notes above are approximately the extent of the documentation, though some videos of using this will be publicly available in a few weeks.
There are updated binary installers for Windows, MacOSX, and Linux. There are also updated "GetLarch.sh" and "GetLarch.bat" scripts that also hopefully fix any earlier problems. If you have any questions, problems, or suggestions, please let me know.
--Matt