Simulating Electronic Spectroscopy using ezSpectra Suite

ezFCF and ezDyson post-processing tools compute vibrational progressions for electronic transitions and photoionization cross sections using Q-Chem’s outputs:

  • Q-Chem: determines relevant electronic states and their optimized geometries, vibrational frequencies, normal modes, and Dyson orbitals (for photoionization).

  • ezFCF: computes Franck-Condon factors (within the double-harmonic approximation) to obtain vibrational structure; Duschinsky rotations can be included.

  • ezDyson: computes photoelectron dipole matrix elements between Dyson orbitals and outgoing photoelectron wavefunction (treated either as a plane wave or a Coulomb wave). The total and differential photoionization cross sections, photoelectron angular distributions (PAD), and anisotropy parameters can be computed.

  • Can be combined with different quantum-chemistry methods.

Formaldehyde photoionization cross section

*Photoelectron spectra of quinoniminyl radicals *