Motif MASTER

The tool for magnetic structure discovering…


About

"Motif MASTER" ("Motif of MAgnetic STructure Enabled by Representations") is the experimental software. The main goal of creating is the investigation of possibility of automation of magnetic structure determination. This software is intended for determination of so-called "motif" of magnetic structure from neutron diffraction data. The term "motif" means here a set of vectors of magnetic moments reflecting the basic features of magnetic structure of compound being under investigation. The aim of this software isn't precision determination of parameters describing a real magnetic structure (for example, angles between moment directions and so on). However, the first stage of magnetic structure determination - determination of "motif" - is most difficult. I hope, using this program will allow to reduce the time outlays for investigations of magnetic structures.


Features

  • As the experimental diffraction data the integral intensities of peaks of powder diffraction pattern are accepted.
  • Determination of the magnetic structure can be carried out by using the basal functions of irreducible representations.
  • This program allows to process not only antiferromagnetic and ferromagnetic structures, but also long periodic (FS, SS, ES) and half-ordered (LSW, TSW).
  • The program doesn't require any preliminary knowledge about the magnetic structure (the knowledge of the propagation vector is nevertheless required) of compound being under investigation.
  • Determination of magnetic structure is carried out by the variational process. The result of this process is a configuration of magnetic moments for which the calculated diffraction pattern gives best consent with experimental one.
  • The tool for making the integral intensities is included. Obtained magnetic structure can be viewed as 3D cell.

What are the advantages of these features in solving the task of determination of "motif"? The using of the integral intensities allows to leave "tiny" details of the diffraction pattern. Thus the number of parameters to vary is essentially reduced and the form of the function is simplified. This in turn allows to use a local optimization algorithm instead of global stochastic one. Using the basal functions allows to reduce the number of parameters even more and guarantees that obtained in the optimization process results will satisfy to the symmetry conditions.

However, the current version of program doesn't perform the calculation of basal function, but use some linear combinations of them.

The program works under Windows XP. The source code is available under GPL. This software is distributed in hope that it will be useful but WITH ABSOLUTELY NO WARRANTY.