GridFire: A New, Open Source, Nuclear Network for Stellar Structure and Evolution

We present a novel nuclear network implementation, GridFire, which has been developed with a focus on efficiency, ease of use, and automatic physical extension. In this first paper we provide a detailed overview of GridFire's numerics, performance characteristics, and a comparison to pre-existing nuclear network implementations pynucastro and MESA's net module. We find that generally GridFire performs similarly to and requires significantly less user input and setup than these current generation nuclear network codes. Further, GridFire has been developed with a flexible "view" based physics engine that allowing researchers to implement domain specific physics without modifying the underlying source code. GridFire has been released under an open-source license, GPL v3.0, and will eventually be incorporated into the forthcoming 4D-STAR stellar structure evolution code.