Package: nonrad
NONRADAn implementation of the methodology pioneered byAlkauskaset al.for computing nonradiative recombination rates from first principles.
The code includes various utilities for processing first principles calculations and preparing the input for computing capture coefficients.
More details on the implementation of the code can be found inour recent paper.
Documentation for the code is hosted onRead the Docs.InstallationNONRAD is implemented in python and can be installed throughpip.
Dependencies are kept to a minimum and include standard packages such asnumpy,scipy, andpymatgen.With pipAs always with python, it is highly recommended to use a virtual environment.
To install NONRAD, issue the following command,$ pip install nonrador to install directly from github,$ pip install git+https://github.com/mturiansky/nonradGoing Fast (Recommended)NONRAD can usenumbato accelerate certain calculations.
Ifnumbais already installed, it will be used;
otherwise, it can be installed by specifying[fast]during installation with pip, e.g.$ pip install nonrad[fast]For DevelopmentTo install NONRAD for development purposes, clone the repository$ git clone https://github.com/mturiansky/nonrad && cd nonradthen install the package in editable mode with development dependencies$ pip install -e .[dev]pytestis used for unittesting.
To run the unittests, issue the commandpytest nonradfrom the base directory.
Unittests should run correctly with and withoutnumbainstalled.UsageA tutorial notebook that describes the various steps is availablehere.
The basic steps are summarized below:Perform a first-principles calculation of the target defect system. A good explanation of the methodology can be found in thisReview of Modern Physics. A high quality calculation is necessary as input for the nonradiative capture rate as the resulting values can differ by orders of magnitude depending on the input values.Calculate the potential energy surfaces for the configuration coordinate diagram. This is facilitated using theget_cc_structuresfunction. Extract the relevant parameters from the configuration coordinate diagram, aided byget_dQ,get_PES_from_vaspruns, andget_omega_from_PES.Calculate the electron-phonon coupling matrix elements, using the method of your choice (seeour paperfor details on this calculation withVASP). Extraction of the matrix elements are facilitated by theget_Wif_from_wavecarsor theget_Wif_from_WSWQfunction.Calculate scaling coefficients usingsommerfeld_parameterand/orcharged_supercell_scaling.Perform the calculation of the nonradiative capture coefficient usingget_C.ContributingTo contribute, see the above section on installingfor development.
Contributions are welcome and any potential change or improvement should be submitted as a pull request onGithub.
Potential contribution areas are:implement a command line interfaceadd more robust tests for various functionsHow to CiteIf you use our code to calculate nonradiative capture rates, please consider citing@article{alkauskas_first-principles_2014,
	title = {First-principles theory of nonradiative carrier capture via multiphonon emission},
	volume = {90},
	doi = {10.1103/PhysRevB.90.075202},
	number = {7},
	journal = {Phys. Rev. B},
	author = {Alkauskas, Audrius and Yan, Qimin and Van de Walle, Chris G.},
	month = aug,
	year = {2014},
	pages = {075202},
}and@article{turiansky_nonrad_2021,
	title = {Nonrad: {Computing} nonradiative capture coefficients from first principles},
	volume = {267},
	doi = {10.1016/j.cpc.2021.108056},
	journal = {Comput. Phys. Commun.},
	author = {Turiansky, Mark E. and Alkauskas, Audrius and Engel, Manuel and Kresse, Georg and Wickramaratne, Darshana and Shen, Jimmy-Xuan and Dreyer, Cyrus E. and Van de Walle, Chris G.},
	month = oct,
	year = {2021},
	pages = {108056},
}