Hi! My name is César Capillas. I work in the Structural Properties and Crystallography Group of the Materials Laboratory and I study the symmetry aspects of structural phase transitions in the Bilbao Crystallographic Server (BCS) project. The BCS provides a free access to several crystallographic databases and tools, very useful in studies related to symmetry, crystallography and phase transitions.
About my Ph. D
My work is focused in computational crystallography. It covers the symmetry aspects of structural phase transitions and the development of the Bilbao Crystallographic Server. Some of the topics are here:
- Infrared and Raman selection rules.
- Structural pseudosymetry analysis.
- Primary and secondary modes in structural phase transitions.
- Transition paths in reconstructive phase transitions.
The Bilbao Crystallographic Server
The Bilbao Crystallographic Server is a web site with crystallographic databases and programs available on-line. It has been operating for about six years and new applications are being added regularly. The programs available on the server do not need a local installation and can be used free of charge. The only requirement is an Internet connection and a web browser. The Bilbao Crystallographic Server is accessible at http://www.cryst.ehu.es. The server is built on a databases core, and contains different shells. The innermost one is formed by simple retrieval tools which serve as an interface to the data from International Tables for Crystallography, Vol. A, Space Group Symmetry, Vol. A1, Symmetry Relations between Space Groups and Vol. E, Subperiodic Groups. The k-vector database includes the Brillouin zones and the wave-vector types for all space groups. As a part of the server one can find also the database of incommensurate structures. The second shell contains applications which are essential for problems involving group-subgroup relations between space groups, while the third shell contains more sophisticated programs for the computation of space-group representations and their correlations for group-subgroup related space groups. There are also programs for calculations focused on specific solid-state physics problems.
My Contribution
Some of my programs are here. The core programs are written in C and the web interfaces in Python & Perl:
- SAM (Symmetry adapted modes - IR/Raman)
- POINT (Point Group Tables)
- DOPE (Degree of Pseudosymmetry Estimation)
- SYMMODES (Primary and Secondary Modes for a Group - Subgroup pair)
- CELLSUB (List of subgroups for a maximum cell multiplication)
- CELLSUPER (List of supergroups for a maximum cell multiplication)
- HERMANN (Classification of subgroups based on Hermann Group)
- COMMONSUBS (Common subgroups of space groups)
- TRANPATH (Transition Paths in Reconstructive Phase Transitions)
