Dialog Box: Symmetry - Cartesian Matrices [ Input1 Menu ] [ Epitaxial Relations dialog]
<Cartesian Mode>
SHAPE in the Cartesian mode (selected with the Operate command in the Modes menu, or by reading in a Cartesian file) requires a file containing the Cartesian symmetry matrices. The auxiliary program SYMGRP writes files which are normally given the suffix .SYM. If you type the name into the edit box, give the full name of the symmetry file, including the .SYM suffix. Some such files, namely those for pentagonal (C5, S10, D5, C5v, C5h, D5h and D5d) and icosahedral (I and Ih) point groups, have already been provided. For other point groups, it will be necessary to run the auxilliary program SYMGRP to generate the file before running SHAPE; see section IV-7 of the Instructions.
The Get Symmetry button reads the file and fills out the symbol, number of matrices and centric/non-centric state, which are printed out below the file name. If this button is not clicked, the file will be read when exiting the dialog.
The file name as entered in the edit box is saved in the data file for the crystal. If the complete path is not given, the Cartesian symmetry file should be in the same directory as the data file. If the file cannot be found when the Get Symmetry button is clicked or when exiting the dialog, you will get an error message and a chance to locate the file with a standard file dialog. The complete path name, as determined in this way or with the Browse button, will then be saved in the data file.
The Cartesian matrices themselves are saved in the SHAPE data file, and the Cartesian symmetry file is read only in this dialog.
The Remove Symmetry button offers the option of converting all faces which have been generated by symmetry to forms, and reducing the symmetry to group 1. The crystal can then be distorted from the ideal habit by changing the central distances of individual faces (through the Forms List dialog). This option is not available unless the crystal has been calculated.
When called from the Input1 menu, this dialog can only modify the main or host crystal of an epitaxial intergrowth. Epitaxial guest crystals are modified from the Epitaxial Relations dialog.
In order to display the symmetry elements themselves in the 3D display mode, the .SYM file must give the orientation of these elements. Old files do not have this information: the new version of SYMGRP supplied the orientation information, but in some cases it may be necessary to modify the files manually - see Symmetry Element Display.