AiiDA plugin for working with CASTEP

A plugin for AiiDA to work with plane-wave pseudopotential DFT code CASTEP. CASTEP has a single binary executable and calculation is primarily controlled by the task keyword. The generic CastepCalculation should work with all tasks, at least in terms of generating input files. Likewise a generic CastepParser class is implemented and can handle parsing most information we are interested in singlepoint, geometryoptimisation, bandstructure/spectral tasks. Most output files are retrieved if present, and it is possible to explicitly request retrieval from the remote computer. The goal of this plugin is not to provide a comprehensive parser of the CASTEP results, but to build a graph of calculations performed for provenance preservation and workflow automation. Input and output of a simple calculation:

or a series of operations and automated calculations:

The raw files can always be extracted from the database and analysed by the post-processing tools of choice. Even better, such tools may be integrated with the AiiDA framework and have the analysis appended to the provenance graph.

Highlights of available features:

• Storing usp/recpot as UspData (sub-class of SingleFileData) in AiiDA database and create/use of pseudo family groups.
• Store OTFG generating strings as OTFGData in AiiDA. Create of family/group are also supported. OTFG library (such as "C19") are represented as a OTFG string works for all elements.
• Preparation of CASTEP input files. Writing cell and parameters files are both supported. Tags in positions_abs block file should also work, e.g LABEL, SPIN, MIXTURE.
• Parsing energy, force, stress from output .castep file and .geom file
• Parsing trajectory from .geom, .ts, .md files.
• Checking errors in .param and .cell files before submitting, using dictionaries shipped from built from CASTEP executable.
• Extra KpointData input node for BS, SEPCTRAL and PHONON tasks.
• Preparing transition state search calculations
• A create_restart function for easy creation of continuation/restart calculations. Input can be altered using param_update and param_delete keyword arguments. Automatic copying/linking of remote check files by AiiDA.
• A get_castep_inputs_summary function to print a summary of inputs of a calculations.
• A compare_with method to compare the inputs of two calculations.

Documentation

Quick glimpse into how to use the plugin for running calculations:

• Running CastepCalculation
• Running CastepBaseWorkChain

Documentation is hosted at Read the Docs: dev version master version

Dependencies

The primary dependency is the aiida_core package. The dependencies are:

• The plugin version 2.0 and above support only aiida_core>=2.0.
• The plugin version 1.0 and above support only aiida_core>=1.0.0b6, <2.
• The plugin version 0.3 support only aiida_core 0.12.x versions.

There is only minor API changes in the aiida_core between v1 and v2, scripts written should be compatible between the two.

Todos and nice-to-haves

• Methods for importing existing calculations
• Support for submitting file based CASTEP calculations.
• At the moment there is no enforcement on the type in Dict input node. For example, setting smearing_width to 0.1 and "0.1" is equivalent, but they will store differently in the database.

How to test

The tests uses the pytest framework. First, install with the dependencies

pip install aiida_core[testing]
pip install aiida-castep[testing]

Then you can run the command pytest from the project directory.