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Match! - Phase Analysis using Powder Diffraction Version 4 Preview

We are currently working on the final steps for the new Match! version 4 that we currently plan to release in the first half of 2024.
The good news first: All Match! version 3 customers whose update permission time has not expired yet will be able to update to the new version free-of-charge!

Here is what's new in version 4:

Profile Fitting Search-Match

The main improvement will be the so-called "profile fitting search-match" (PFSM), a powerful, innovative alternative to the proven peak-based search-match functionality for qualitative phase analysis. The new function fits the profile calculated from each candidate entry of the current reference database (or answer set) to the experimental profile on the fly, so that the sometimes ambiguous peak searching is no longer required for qualitative phase analysis.

The new feature works without additional software, i.e. no Rietveld software (like FullProf) is required! In fact, no Rietveld refinement is performed actually, i.e. no structural parameters are currently refined.

Here is how it works: During profile fitting search-match, Match! calculates a profile pattern for every entry of the reference database (or answer set), and fits both the intensity scale factor as well as the 2theta shift in order to get an optimum agreement with the experimental profile diffraction pattern. The candidate entries are ranked according to the Rwp values resulting from the individual fitting calculations, or, to be exact, to the reduction of the Rwp value D(Rwp) calculated from the selected phases that the corresponding new candidate entry would achieve.

The main advantage of profile fitting (PF) search-match is the fact that no peak searching is required, thus avoiding the ambiguities that may arise from this.

Another important advantage (compared to the Rietveld refinement search-match approaches cited below) is that PF search-match in Match! can use arbitrary peak data reference databases, like the COD, ICDD PDF-2, PDF-4, own diffraction patterns etc. The knowledge of atomic parameters for the candidate phases is not required.

While the success rate of this new approach is definitely higher than the "classical" (peak-based) approach (especially with minor or trace phases), there is certainly one main drawback: The calculation time is significantly longer. In order to compensate for this to a certain degree, the profile fitting search-match by default runs in parallel on all available cores of your CPU. It is also possible to restrict the calcuation to a lower number of CPU cores (or even to a single core), in order to keep your computer more "responsive" for other tasks.

Here is a screenshot of the new version, showing the new profile fitting search-match function in action on a Cement sample:

Profile fitting search-match as it is now implemented in Match! has not been invented "out of the blue" but has been inspired by other approaches, most of which use Rietveld refinement for qualitative phase analysis:

• Profex / BGMN using automatic Rietveld refinements for each candidate phase
• Luca Lutterotti: "Full Profile Search Match (FPSM)": Lutterotti, L. et al., "Full-profile search-match by the Rietveld method", J. Appl. Cryst. 52 (2019).
• SNAP-1D: C. J. Gilmore, G. Barr and J. Paisley, "High-throughput powder diffraction. I. A new approach to qualitative and quantitative powder diffraction pattern analysis using full pattern profiles", J. Appl. Cryst. 37, 231-242 (2004)
  and
  Barr, G., Gilmore, C. J. & Paisley, J., "SNAP-1D: a computer program for qualitative and quantitative powder diffraction pattern analysis using the full pattern profile", J. Appl. Cryst. 37, 665-668 (2004).

Further Improvements in Match! 4

• Continuous display of already found results during normal (peak-based) search-match
• New menu command "Entries / Automatic entry selection" selects matching phases automatically. The minimum required Rwp reduction (that is also used for automatic selection of entries) can be adjusted in the "PF search-match" section on the "Search-Match" tab of the "Options" window.
• New menu command "Quantify / Rietveld refinement (FullProf)" (keyboard shortcut: <Ctrl+Alt+R>) uses the currently selected schedule (-> Rietveld options) to perform an automatic Rietveld refinement calculation using FullProf.
• Match! 4 will become available for Windows (64-bit and 32-bit), macOS and Linux 64-bit.
• For macOS there will be separate versions for ARM (Apple Silicon) and Intel processors, in order to improve the calculation speed while at the same time reducing the memory overhead.