The XTAL Program

The program can also be used to perform the following calculations...

• Generate the coordinates of crystalline model with more than one unit cell
• Determine the coordination number of the atoms in the structure
• Find which atom pairs have a separation within a specified range
• Determine the bond angles of the structure
• Calculate the distortion of the polyhedra in the structure

It is recommended to run XTAL from a command prompt window (not by double-clicking an icon) because the output can be followed better in this way.

The input to the XTAL is a .XTAL file. This can be created manually by following the description in XTAL manual RAL-03-063 report.pdf. Or for a crystalline model it can be generated automatically using the MAKEX program on a file from a crystal structure database.

The principal output from XTAL is a .RDF file, which contains the partial radial distribution functions for the model.

The correlation functions calculated by XTAL are not broadened for the effects of thermal motion or real-space resolution - this broadening can be done by using the RDF program.

For crystalline models, there is a limit on the longest interatomic distance that can be considered, due to the way that the xtal program holds the whole model in memory at once. However, an alternative version of the program called XTALM is available, for which the longest interatomic distance is almost unlimited. XTALM uses a different algorithm, which does not consider the whole model at once, but instead at any one time considers only the origin unit cell and one additional unit cell (the 'mirror' cell).

A version list for XTAL is here.

Last Updated 23 Apr 2014 by Alex Hannon