This repository holds all the code, auxiliary files, and intermediate files used in Ranjan, Wordsworth & Sasselov 2017b. Using this material, one can replicate every one of the figures used in our paper, as well as run models of one's own formulation. The anticipated use cases are: 1. Testing/validating the findings of Ranjan, Wordsworth & Sasselov (2017) 2. Using the Ranjan, Wordsworth & Sasselov radiative transfer model to compute UV surface fluence for user-defined atmospheres and surfaces. If making use of this code or the generated auxiliary files, please cite the descriptor paper: Ranjan, S, Wordsworth, Robin D. and Sasselov, Dimitar D. "The Surface UV Environment on Prebiotic Planets Orbiting M-dwarfs: Implications for Prebiotic Chemistry & Need for Experimental Follow-Up". Submitted to the Astrophysical Journal (2017). arXiv: 1705.02350   This version represents the state of the code at the time of paper acceptance.