Module spectroscopy 

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.

Modules

hessian

Semi-numerical Hessian matrix computation.

ir_intensities

IR intensities from dipole derivatives.

transition_dipoles

Electric dipole transition moments.

Structs

NmrShieldingResult

Result of GIAO NMR calculation.

ScfInput

Converged SCF data needed by spectroscopy methods.

ShieldingTensor

NMR shielding tensor for a single nucleus.

SpectroscopyResult

Result of sTDA UV-Vis calculation.

StdaConfig

Configuration for sTDA calculation.

TransitionInfo

Information about a single electronic transition (UV-Vis).

Functions

compute_nmr_shieldings

Compute NMR shielding tensors using the GIAO method.

compute_nmr_shieldings_for_nucleus

Compute GIAO shieldings for a specific target nucleus.

compute_stda

Compute sTDA excitation energies and oscillator strengths.

shieldings_to_shifts

Convert shielding tensors to a summary result.