shnitsel-tools: A Toolkit for the Full Lifecycle of Surface Hopping Trajectory Data

Abstract

Trajectory surface hopping (SH) simulations are essential for modeling excited-state dynamics, yet their analysis remains complex and fragmented. Existing tools provide access to basic quantities, but extracting deeper mechanistic insight, especially across multiple molecules, often requires extensive manual work and custom scripting. To address this gap, we present shnitsel-tools (st), an integrated software package for the streamlined analysis, filtering, and visualization of SH data. Supporting automated and reproducible workflows, it enables efficient interpretation of excited-state simulations across diverse systems. As a demonstration, we apply st in a walkthrough example analyz- ing photoinduced dynamics across chemical compound space for a series of alkenes (C_nH_2n , with n = {2, 3, 4}) and CNH₄⁺ as illustrative cases. This highlights how the toolkit facilitates comparative studies and mechanistic discovery across the chemical compound space of molecules with similar molecular scaffolds.