CASTEP > Tasks in CASTEP > Setting up CASTEP calculations > Manipulating files

Manipulating files

CASTEP is a file-based application which means that all input information is provided in various ASCII text files and the output is delivered in a mixture of text and binary files. This section describes some file handling issues which may arise, especially when the CASTEP server is run in a standalone mode and not via a gateway.

Input files

CASTEP allows you to save input files, for subsequent manual editing instead of running the job directly.

To save input files

  1. Choose Modules | CASTEP | Calculation from the Materials Studio menu bar.
  2. Click the Files... button to open CASTEP Job Files dialog.
  3. Click the Save Files button.

The Save Files button is enabled only if a suitable 3D model document is active.

Only one input file, .param, is displayed in the Project Explorer. This file contains the parameters specified using the CASTEP interface. However, it also contains a few parameters that allow you to access functionality which is not supported though the interface. The other input files are hidden, since they are unlikely to be edited manually.

Input files can be run on a server after they have been edited:

To run CASTEP using an existing set of input files

  1. Choose Modules | CASTEP | Calculation from the Materials Studio menu bar.
  2. Click the Files... button to open CASTEP Job Files dialog.
  3. Click the Run Files button.

The Run Files button is enabled only if a suitable .param file is active.

If your server does not support the gateway protocol, you may have to run CASTEP in standalone mode using the RunCASTEP.sh or RunCASTEP.bat files provided with the installation.

In such circumstances it is necessary to copy all the input files from the Materials Studio Project folder to the appropriate directory on the server machine. The scripts required for standalone execution are provided with accompanying RunCASTEP.Readme files that explain, in detail, how to use them. Alternatively, you can obtain help by typing one of the following:

RunCASTEP.sh -h

RunCASTEP.sh

The Materials Studio Project folder does not contain the pseudopotential files required to run a job. When transferring input files to the server, you must therefore determine which pseudopotential files are required by examining the .cell file. Then you must locate those potential files in Materials Studio installation, typically in a sub-directory called share\Resources\Quantum\Castep and copy the required files to the same directory on the server as the rest of the input files.

Output files

Only one output file, .castep, is displayed in the Project Explorer. However, there are many more files created during a CASTEP run. These are hidden by Materials Studio. All of these output files are placed in the correct Materials Studio Project folder automatically, when the job is run using the Gateway. However, if CASTEP is run in standalone mode, the output files must be copied manually from the server to the appropriate Project folder.

Some output files can be quite large. If these files are not likely to be required to restart the job, then it is recommended that you delete or archive them periodically.

Restarting a CASTEP calculation

It is not possible to restart a completed CASTEP job automatically via the interface. However, there are circumstances in which you may wish to do this, for example, if you are running a geometry optimization which does not converge in the given number of steps, or a you wish to continue your calculation with manually modified runtime parameters. To restart such jobs you should edit .param file and add the CONTINUATION keyword to the file.

Any additional changes to this file may make it impossible to restart the CASTEP job successfully.

It is possible to remove everything from .param and leave only the CONTINUATION line. This will ensure that all of the settings remain exactly the same as those from the previous run.

In order to restart a job, the output files from the previous run must be present in the Project folder. This check and the subsequent transfer of the files to the server happens automatically whenever CASTEP is used to run an existing file set or to calculate additional properties.

See Also:

CASTEP file formats
CASTEP keywords

Accelrys Materials Studio 8.0 Help: Wednesday, December 17, 2014
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