Valence Photoelectron Spectroscopy


ezDyson picture
ezSpectrum picture

Q-Chem electronic structure calculations can be combined with two freely-available spectral analysis tools to model photoelectron spectroscopy. A workflow for this procedure is the following:

  • Q-Chem: determine the ionized states and the corresponding Dyson orbitals at the EOM-IP-CCSD level of theory. Calculated optimized geometries, vibrational frequencies, and normal mode vectors of the ground and ionized states.

  • ezDyson: calculate the photoelectron dipole matrix elements between Dyson orbitals and outgoing photoelectron wavefunctions, thus determine differential photoionization cross sections. The photoelectron can be treated either as a plane wave or a Coulomb wave. The total photoionization cross sections, photoelectron angular distributions (PAD), and anisotropy parameters (β) are also calculated.

  • ezSpectrum: analytic calculation of Franck-Condon factors (within the double-harmonic approximation) to obtain vibrational structure. Duschinsky rotations can be included.


Formaldehyde photoionization cross section

ezDyson paper picture

Photoelectron spectroscopy with vibrational structures of quinoniminyl radicals

ezSpectrum paper picture