  Point defects in semiconductor crystals provide a means for carriers to
recombine nonradiatively. This recombination process impacts the performance of
devices. We present the Nonrad code that implements the first-principles
approach of Alkauskas et al. [Phys. Rev. B 90, 075202 (2014)] for the
evaluation of nonradiative capture coefficients based on a quantum-mechanical
description of the capture process. An approach for evaluating electron-phonon
coupling within the projector augmented wave formalism is presented. We also
show that the common procedure of replacing Dirac delta functions with
Gaussians can introduce errors into the resulting capture rate, and implement
an alternative scheme to properly account for vibrational broadening. Lastly,
we assess the accuracy of using an analytic approximation to the Sommerfeld
parameter by comparing with direct numerical evaluation.
