//! Advanced Spectroscopy — Core Module
//!
//! Contains spectroscopic methods promoted from experimental:
//! - **sTDA UV-Vis**: Simplified Tamm-Dancoff approximation for electronic excitations
//! - **GIAO NMR**: Gauge-including atomic orbitals for chemical shifts
//!
//! These complement the existing topology-based NMR (HOSE codes) and
//! numerical IR vibrational analysis in the core.
//!
//! ## sTDA UV-Vis
//!
//! Requires a converged SCF result (from HF-3c, PM3+basis, or EHT).
//! Provides excitation energies, wavelengths, and oscillator strengths.
//!
//! ## GIAO NMR
//!
//! Quantum-mechanical NMR chemical shifts. More accurate than topological
//! (HOSE code) NMR but requires 3D coordinates and a SCF calculation.
//! The user can choose fast topological NMR or slower quantum NMR.
pub use ;
pub use ;
pub use ;