CASTEP FAQ

Q) How do I cite CASTEP in a publication?
A) For versions of CASTEP up to and including v3.1 you should cite
M. D. Segall, P. L. D. Lindan, M. J. Probert, C. J. Pickard, P. J. Hasnip, S. J. Clark, M. C. Payne J. Phys.: Cond. Matt. 14(11) pp.2717-2743 (2002)
and for later versions you should cite
S. J. Clark, M. D. Segall, C. J. Pickard, P. J. Hasnip, M. J. Probert, K. Refson, M. C. Payne Zeitschrift für Kristallographie 220(5-6) pp.567-570 (2005)

Q) How do I compile CASTEP from source?
A) Most users will be supplied with a range of pre-compiled binaries for a range of different platforms. If however you want to add new features or run on a different platform, then you will need to compile CASTEP from source. CASTEP is written in Fortran90, so you will need an f90 compiler, and if you want to take advantage of its parallel processing abilities, you will also need appropriate hardware and an MPI installation. For more details, see this separate README.INSTALL help file.

Q) How do I know what keywords to set and where?
A) Materials Studio provides a GUI to setting up your input files. The alternative is to set-up the .param and .cell file manually. To do this, you need to know about the recognised keywords and their functionality. In the workshops section you will find that there is lots of information about the different keywords and the cell and param files.
You can also use the built-in help facility, e.g.

to get more information on using castep, or

to return a condensed listing of all keywords that have the string keyword in their associated help text, etc.

Q) How do I know which version of CASTEP I have?
A) The header of the .castep file will contain a line such as

Q) Is there a difference between the academic and Materials Studio versions of CASTEP?
A) No. The source code is the same in both cases. However, the Materials Studio GUI only exposes a subset of the full functionality of CASTEP. To gain the full functionality you need to edit the input files.

Q) How do I add a new feature to CASTEP?
A) Presuming you have access to the CASTEP source, then speak to the CDG member who is closest to the area of functionality you are interested in to make sure you aren't duplicating work done elsewhere.

Q) How do I animate an MD or Geometry Optimisation run?
A) These can be animated directly within Materials Studio. Or if you prefer, you can use the Source/Tools/md2xyz program to convert the trajectory file to .xyz format which can then be visualised using many other packages. See the links page for some example programs.

Q) How can I get a nice picture from Materials Studio into another document?
A) Use Materials Studio to make a really large bitmap:

• Set up the view you want. Think about the background (you probably want white).
• Choose View -> Display-Options and increase the "Quality" to maximum (this can really slow things down, especially if you have a lot of atoms.
• Choose File -> Export. Change the "Export as Type" to "Structure Bitmap". Under "Options" increase the image size. A width of 4600 pixels gives a bitmap of about 35Mb.

Then convert that to your compressed format of choice. For web usage (or PowerPoint) you probably want a png or jpeg file but for latex you want an eps file. It is possible to produce high quality eps files well under 100KB in this way.

Q) How do I set up *.cell files from diffraction structures?
A) Crystal structures from a crystallographic database (eg the CDS) are usually in pdb or cif format. Materials Studio can read pdb and cif file directly, but versions prior to 3.0 did have some issues with reading in pdb files and there may still be some issues with files for non-orthorhombic systems. A more reliable route is to use Keith Refson's cteprouts package which is included within the CASTEP source distribution as Source/Tools/cteprouts. This contains perl scripts such as pdb2cell to convert pdb to cell files, and can also create supercells and translate atoms back into the primitive cell, etc.

Q) What can I do if my question has not been answered by this webpage?
A) There are a growing number of CASTEP questions and answers on the CASTEP forum at JISC. You should browse the archives to see if your question has already been answered before, and if not, then ask it there. Many members of the CASTEP user community as well as all the CDG will then see your message and be able to respond.

If you have any comments about these pages, you can email Matt Probert as mijp1 at york.ac.uk