Wavefunction-Free Framework for Nonlinear Photocurrent Prediction in Weyl Semimetals

Predicting nonlinear electromagnetic responses in quantum materials remains computationally challenging because conventional approaches depend explicitly on many-body wavefunctions. We introduce a wavefunction-free framework that directly maps band-structure parameters to nonlinear optical responses, demonstrated using the circular photogalvanic effect (CPGE) in Weyl semimetals. By eliminating wavefunction dependence, our approach achieves over three orders of magnitude speedup compared with traditional methods. Applying this framework to various Weyl materials, we identify Ta₃S₂ as exhibiting photocurrents an order of magnitude larger than in TaAs, with further enhancement possible under strain. We also extend the method to derive a wavefunction-free formulation of the Berry-curvature dipole, underscoring its generality. This work establishes a scalable route for rapid screening and design of nonlinear optical properties in topological quantum materials.