SARAh – Simulated Annealing and Representation Analysis

 

News – Feb 2022. The web version of SARAh Refine for FullProf has been released. It reproduces the core features of SARAh Refine for Windows in a browser and has introduces new refinement ideas : http://fermat.chem.ucl.ac.uk/spaces/willsgroup/web-software/sarah-refine-fullprof/

(Click icon to download combined install file from Dropbox)

The SARAh suite is made up of 2 separate programs that perform symmetry calculations and magnetic structure analysis :

SARAh Representational Analysis –

Performs the calculations of Representational Analysis. These allow the determination of atomic displacements or magnetic structures that can accompany a second-order phase transition. Output files includes a tailored summary with cut-and-paste tables written in LaTeX. (Win9x, 2000, Vista and Windows 7) [1]

SARAh Refine –

Is an example of a ‘metaprogram’. SARAh refine was developed to add new functionality to the standard Rietveld programs GSAS, FullProf and TOPAS, i.e. to allow them to refine magnetic structures in terms of the basis vectors (symmetry modes) generated by SARAh Representational Analysis and the calculations of group theory. [1]

For GSAS, previously limited to a symmetry description in terms of magnetic space groups, SARAh Refine allowed far more complex structures to be analysed. Data refinement can be carried out using reverse-Monte Carlo and Simulated Annealing. SARAh Refine has features to help non-specialised users analyse their data, by setting up the magnetic phase automatically, refining the moment orientations in terms of basis vectors with a ‘point and click’ interface, and interfacing with FullProf Studio to enable viewing of the magnetic structure.

For FullProf, SARAh Refine automatically sets up the pcr file for the magnetic refinement, edits the pcr file with the different magnetic basis vectors selected with a ‘point and click’ interface, and enables the searching of magnetic propagation vectors with reverse-Monte Carlo routines and Brillouin zone indexing. [2]

For TOPAS, SARAh-Refine automatically makes model magnetic phases and allows use of Shubnikov or basis vector descriptions.

SARAh Refine works to increase the functionality of GSAS, FullProf and TOPAS. It runs under Win9x, 2000, Vista and Windows 7.

-Always be up to date! The SARAh suite of software automatically checks for updates every time you use it, so bug improvements are passed on immediately.

[1] Wills,A.S (2000). A new protocol for the determination of magnetic structures using Simulated Annealing and Representational Analysis- SARAh. Physica B 276, 680-681.

[2] Wills,A.S. (2009). Indexing magnetic structures and crystallographic distortions from powder diffraction: Brillouin zone indexing. Z Kristallogr Suppl 30 39-44