[cctbxbb] Comparison of Crystal Structures

David Lonie loniedavid at gmail.com
Fri Jan 13 10:49:41 PST 2012

Hi list,

I have written an open-source (BSD-licensed) algorithm to compare two
crystal structure descriptions and identify whether they describe the
same underlying structure. The algorithm is capable of detecting
degenerate descriptions (meaning unit cell vectors + atomic positions
and types) even in the presence of the "real-world" issues confronting
computational crystallographers (choice of unit cell representation
and offset, rotations, reflections, and numerical noise). The
algorithm returns a boolean match using customizable tolerances.

I just wanted to inform the mailing list of this, in case such
functionality is needed by your user community. The code, XtalComp, is
written in C++ and is easy to interface with, having no external
dependencies. The liberal license would allow it to be included with
the cctbx sources and interfaced with cctbx code if desired. The code
uses the CMake build system, but the simple nature of the sources
would allow trivial porting to SCons.

There is a web interface to the code here:

Also on that page are links to the journal article describing the
algorithm, as well as a free download of the preprint version of the
article. The code is available on Github

Thanks for your time, and I hope that someone out there will find this
code useful :-) Keep up the good work!


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