Valence Photoelectron Spectroscopy

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.