pymatgen-analysis-defects 2022.12.20

Pymatgen extension for defects analysis

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This package is an extension to pymatgen for performing defect analysis. The package is designed to work with VASP inputs and output files and is meant to be used as a namespace package extension to the main pymatgen library. The new module has been redesigned to work closely with atomate2.

While the atomate2 automation framework is not required for this code to be useful, users are strongly encouraged to to adopt the atomate2 framework as it contains codified “best practices” for running defect calculations as well as orchestrating the running of calculations and storing the results.

Non-exhaustive list of features:

Reproducible definition of defects

Defects are defined based on the physical concept they represent, independent of the calculation details such as simulation cell size. As an example, a Vacancy defect is defined by the primitive cell of the pristine material plus a single site that represents the vacancy site in the unit cell.

Formation energy calculations

The formation energy diagram is a powerful tool for understanding the thermodynamics of defects. This package provides a simple interface for calculating the formation energy diagram from first-principles results. This package handles the energy accounting of the chemical species for the chemical potential calculations, which determines the y-offset of the formation energy. This package also performs finite-size corrections for the formation energy which is required when studying charged defects in periodic simulation cells.

Defect Position

Identification of the defect positions in a simulation cell after atomic relaxation is not trivial since the many atoms can collectively shift in response to the creation of the defect. Yet the exact location of the defect is required for the calculation of finite-size corrections as well as other physical properties. We devised a method based on calculating a SOAP-based distortion field that can be used to identify the defect position in a simulation cell. Note, this method only requires the reference pristine supercell and does not need prior knowledge of how the defect was created.

Defect Complexes

Multiple defects can be composed into defect complexes. The complex is can be treated as a normal defect object for subsequent analysis.

Capture coefficients

Coming Soon … Radiative and Non-radiative capture coefficients at defect centers using semi-classical approaches.

Previous versions of the defects code

This package replaces the older pymatgen.analysis.defects modules. The previous module was used by pyCDT code which will continue to work with version 2022.7.8 of pymatgen.

Contributor

• Lead developer: Dr. Jimmy-Xuan Shen

• This code contains contributions from the original defects analysis module of pymatgen from Dr. Danny Broberg and Dr. Shyam Dwaraknath.