ConeZen: A Python Toolkit for Characterizing and Visualizing Conical Intersection Topologies

ConeZen is a lightweight, open-source Python package designed to characterize and visualize the branching plane topology at a conical intersection (CI). The geometry of a CI's potential energy surfaces is critical in determining the pathways for ultrafast, non-radiative electronic transitions, which are fundamental to a variety of important processes such as vision, photosynthesis, and the photostability of DNA. By utilizing the output from standard quantum chemistry programs (tested with SHARC-OpenMolcas), ConeZen efficiently computes key topological descriptors of the CI seam and renders intuitive 3D potential energy surfaces. This powerful tool enables researchers to move seamlessly from complex numerical data to a more intuitive and quantitative understanding of the CI landscape. This, in turn, facilitates the prediction of the outcomes of photochemical reactions, making ConeZen an invaluable asset for the computational chemistry and photochemistry communities.