Fuzzy Neural Network Performance and Interpretability of Quantum Wavefunction Probability Predictions

TL;DR

This paper compares neural networks and neuro-fuzzy systems in predicting quantum wavefunction probabilities, highlighting a trade-off between accuracy and interpretability, with implications for quantum chemistry modeling.

Contribution

It demonstrates that ANFIS offers interpretable models aligned with quantum principles, while ANNs provide higher accuracy, advancing hybrid approaches in quantum simulations.

Findings

ANN achieved R^2 = 0.99, outperforming ANFIS's 0.95

ANFIS's Gaussian membership functions encode electron localization

Fuzzy rules reflect quantum superposition and symmetry principles

Abstract

Predicting quantum wavefunction probability distributions is crucial for computational chemistry and materials science, yet machine learning (ML) models often face a trade-off between accuracy and interpretability. This study compares Artificial Neural Networks (ANNs) and Adaptive Neuro-Fuzzy Inference Systems (ANFIS) in modeling quantum probability distributions for the H$_{2}^+$ ion, leveraging data generated via Physics-Informed Neural Networks (PINNs). While ANN achieved superior accuracy (R$^2$ = 0.99 vs ANFIS's 0.95 with Gaussian membership functions), it required over 50x more parameters (2,305 vs 39-45). ANFIS, however, provided unique interpretability: its Gaussian membership functions encoded spatial electron localization near proton positions ($\mu = 1.2 A$), mirroring Born probability densities, while fuzzy rules reflected quantum superposition principles. Rules prioritizing the internuclear direction revealed the system's 1D symmetry, aligning with Linear Combination of Atomic Orbitals theory--a novel data-driven perspective on orbital hybridization. Membership function variances ($\sigma$) further quantified electron delocalization trends, and peak prediction errors highlighted unresolved quantum cusps. The choice of functions critically impacted performance: Gaussian/Generalized Bell outperformed Sigmoid, with errors improving as training data increased, showing scalability. This study underscores the context-dependent value of ML: ANN for precision and ANFIS for interpretable, parameter-efficient approximations that link inputs to physical behavior. These findings advocate hybrid approaches in quantum simulations, balancing accuracy with explainability to accelerate discovery. Future work should extend ANFIS to multi-electron systems and integrate domain-specific constraints (e.g., kinetic energy terms), bridging data-driven models and fundamental physics.