Bidirectional neural networks for global nucleon-nucleus optical model calculations
Phys. Rev. C 114, 014620 – Published 15 July, 2026
DOI: https://doi.org/10.1103/qw54-df4l
Abstract
Modern nuclear data evaluation increasingly requires not only accurate scattering calculations but also efficient methods for uncertainty quantification and parameter optimization, tasks that benefit from differentiable solvers amenable to gradient-based algorithms. I present a neural network emulator based on bidirectional liquid neural networks that provides a differentiable mapping from the optical potential to scattering wave functions. The key innovation enabling generalization across the parameter space is the use of phase-space coordinates that normalize the oscillation wavelength regardless of projectile energy, allowing a single network to span 1 to 200 MeV. Trained on Numerov solutions for 12 target nuclei ( to ), both protons and neutrons, and partial waves up to , the network achieves an overall relative error of 0.6%. The predicted wave functions yield accurate -matrix elements and elastic scattering cross sections, reproducing diffraction patterns spanning four orders of magnitude. Importantly, the model generalizes successfully to nuclei not included in training (, and ) with comparable accuracy, demonstrating that it has captured the smooth functional dependence encoded in the Koning-Delaroche (KD02) parametrization rather than memorizing specific targets. The differentiable nature of the trained model is the key prerequisite for gradient-based optimization of optical model parameters and uncertainty quantification, which I identify as the principal direction for future work.