Rayleigh 1894 + Schrödinger 1926 nondegenerate-perturbation; modern modern foundational text + 2024 ML-driven Padé-perturbation acceleration.
Rayleigh 1894 + Schrödinger 1926 nondegenerate-perturbation; modern modern foundational text + 2024 ML-driven Padé-perturbation acceleration.