ISODISTORT

Version 5.4, May 2012

Harold T. Stokes. Branton J. Campbell, and Dorian M. Hatch
Department of Physics and Astronomy, Brigham Young University, Provo, Utah

ISODISTORT is a tool for exploring the structural distortion modes of crystalline materials. It provides a user-friendly interface to many of the algorithms used by the Isotropy Software Suite, allowing one to generate and explore distortion modes induced by irreducible representations of the parent space-group symmetry. It also provides a Java applet for visualizing and interactively manipulating the free parameters associated with these modes. See the complete ISODISTORT help file for detailed explanations and a brief tutorial.

See the Tutorial at the IUCr Software Fayre, Madrid, 2011

Begin by entering the structure of parent phase: (help)

Get started quickly with a cubic perovskite example.

Import parent structure from a CIF structure file

If you don't have a parent CIF, create one using ISOCIF.

Alternatively, you can begin with a previously-saved distortion: (help)

Get started quickly with a distorted perovskite example. (Select this link and click "OK" on the next page to test your Java installation.)

Import an ISODISTORT distortion file

In published works that include or utilize ISODISPLACE or ISODISTORT output, please cite B. J. Campbell, H. T. Stokes, D. E. Tanner, and D. M. Hatch, "ISODISPLACE: a web-based tool for exploring structural distortions", J. Appl. Cryst. 39, 607--614 (2006). Download PDF reprint.

New features:

Version 5.4:
(1) Resolved some problems related to the decomposition of magnetic structures and the output of magnetic symmetry modes, changed the way that magnetic symmetry modes are handled, and changed the way that symmetry mode information is presented in CIFs. If you have old distortion files containing magnetic symmetry modes in supercells with non-orthogonal axes, we recommend that you import and resave them. If you have previously decomposed a magnetic structure where lattice strains were also present, your magnetic mode amplitudes will be slightly off -- redo the decomposition to correct them. If you use CIF-formatted symmetry-mode information (a format in progress), and want to better understand what has changed, feel free to contact us for more information.

Version 5.3:
(1) Superposed IRs with incommensurate k points implemented.
(2) New matrices for many IRs. These new matrices keep the contributions from different k vectors separated in the order parameter.
(3) By popular demand, improved human-readable format for saved distortion files. This fixes the problem with distortion files becoming invalid after short periods of time. Unfortunately, this means that all distortion files generated with earlier versions of ISODISTORT will be invalid. However, we expect that the new distortion files will be backwards compatible with all future versions of ISODISTORT.

Version 5.2:
(1) Amplimode-format output for FullProf

Version 5.1:
(1) Modes details for incommensurate structures. Additional information about individual atoms is given in a new option, "Complete modes details."
(2) Incommensurate magnetic structures for a single IR in search method 2. Implementation of this feature is based on private communication from J. M. Perez-Mato.
(3) Basic space-group setting option for incommensurate structures.

Version 5.0:
(1) Changed name from ISODISPLACE to ISODISTORT, since atomic displacement is only one of four different types of distortions treated.
(2) Magnetic moments and magnetic space groups.
(3) Improved decomposition algorithm in method 4 on the search page, including an optional specification of space-group origin.

Version 4.8:
(1) On the Search page, the user can select what kinds of distortions to consider. Ordering distortions are no longer shown by default, but must be selected here.
(2) User can now save interactive applet images to file. Note that allowing an internet-based applet to save files to your computer requires first accepting a security certificate that is presented when you start the applet. Everything but the new "Save Image" feature should still work if you reject the certificate.

Version 4.7:
(1) The format of the data sent by ISODISPLACE to the interactive java applets (isoDisplaceApplet.jar and isoDiffractApplet.jar) has been changed in order to make it easier for other software packages to utilize the applets.

Version 4.6:
(1) Powder diffraction capabilities added to interactive applet.
(2) Mode decomposition utility now automatically searches for probable superlattice-basis candidates.

Version 4.5:
(1) Fixed the applet so that is runs with the new version of Apple JVM.
(2) Added TOPAS.STR button to export a file for structure refinement using distortion-mode amplitudes.

Version 4.4:
(1) New method for normalization of mode amplitudes
(2) Modes details page
(3) Additional option for search method 3

Version 4.3:
(1) Includes atomic occupancy.

Version 4.2:
(1) ISOCIF utility for creating and modifying CIF files.
(2) Improved choices for monoclinic and triclinic unit cells of distorted structures.

Version 4.0:
(1) Order parameters and slide bars for atomic ordering.
(2) Incommensurate distortions leading to (3+1)-dimensional superspace groups.
(3) Width of applet controlled by user input so that it can fit on low-resolution screens.
(4) Mode decomposition of large structures.
(5) CIF output containing linear transformation between atomic coordinates and mode amplitudes.

Version 3.3:
Interactive visualization of single-crystal x-ray and neutron diffraction patterns