ISODISPLACE 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. isodisplace was developed by Harold T. Stokes, Branton J. Campbell, and Dorian M. Hatch.

Preparation for the workshop

Before coming to this workshop, you should test your version of Java. Direct your internet browser to stokes.byu.edu/bilbao/test.htm. If graphics appears on the screen, your version of Java is fine. If not, then you need to update your version of Java. For Windows, go to java.com/getjava. For Macs, use the update utility.

Also, download the zip file at stokes.byu.edu/bilbao/cif.zip and extract the files into a folder named isodisplace. You will use these files during the workshop.

Part 1. Introduction to the Java applet

1. CaTiO₃ (stokes.byu.edu/bilbao/CaTiO3.htm)
2. LaMnO₃ (stokes.byu.edu/bilbao/LaMnO3.htm)
3. WO₃ (stokes.byu.edu/bilbao/WO3.htm)
4. LiAlO₂ (stokes.byu.edu/bilbao/LiAlO2.htm)

Part 2. Using ISODISPLACE: Method 4

Mode decomposition of a distorted structure

If you know the structure of a distorted crystal and the structure of its undistorted parent (either from a phase at higher temperature or simply derived from the distorted structure), you can use method 4 to find the distortion and decompose it into symmetry-adapted modes of the parent. We will apply this method to CaTiO₃.

The structure of CaTiO₃ is reported in S. Sasaki, C. T. Prewitt, J. D. Bass and W. A. Schulze, “Orthorhombic Perovskite CaTiO₃ and CdTiO₃: Structure and Space Group,” Acta Cryst. (1987), C43, 1668–1674.

Space Group: #62 Pnma (orthorhombic)

a = 5.4423, b = 7.6401, c = 5.3796

Ca (4c) 0.03602, 1/4, −0.00676

Ti (4b) 0, 0, 1/2

Supplementary Material