title: Computing UV/vis spectra from the adiabatic and vertical Franck-Condon schemes with the use of Cartesian and internal coordinates.
abstract: We address the effects of using Cartesian or internal coordinates in the adiabatic Franck-Condon (AFC) and vertical Franck-Condon (VFC) approaches to electronic spectra. The adopted VFC approach is a simplified variant of the original approach [A. Hazra, H. H. Chang, and M. Nooijen, J. Chem. Phys. 151, 2125 (2004)], as we omit any contribution from normal modes with imaginary frequency. For our test molecules ranging from ethylene to flavin compounds, VFC offers several advantages over AFC, especially by preserving the properties of the FC region and by avoiding complications arising from the crossing of excited-state potential surfaces or from the failure of the harmonic approximation. The spectral quality for our target molecules is insensitive to the chosen approach. We also explore the effects of Duschinsky rotation and relate the need for internal coordinates to the absence of symmetry elements. When using Duschinsky rotation and treating larger systems without planar symmetry, internal coordinates are found to outperform Cartesian coordinates in the AFC spectral calculations.
authors.affiliation: Max-Planck-Institut für Kohlenforschung, Kaiser-Wilhelm-Platz 1, 45470 Mülheim an der Ruhr, Germany.
authors.forename: Jan P
authors.initials: JP
authors.lastname: Götze
authors.affiliation: Max-Planck-Institut für Kohlenforschung, Kaiser-Wilhelm-Platz 1, 45470 Mülheim an der Ruhr, Germany.
authors.forename: Bora
authors.initials: B
authors.lastname: Karasulu
authors.affiliation: Max-Planck-Institut für Kohlenforschung, Kaiser-Wilhelm-Platz 1, 45470 Mülheim an der Ruhr, Germany.
authors.forename: Walter
authors.initials: W
authors.lastname: Thiel
mesh_terms: D003198:Computer Simulation; D005030:Ethylenes / Q000737:chemistry*; D005415:Flavins / Q000737:chemistry*; D008027:Light; D011090:Polyenes / Q000737:chemistry*; D011789:Quantum Theory; D014466:Ultraviolet Rays
chemical_list: D005030:Ethylenes; D005415:Flavins; D011090:Polyenes; C512191:1,3,5-hexatriene; C036216:ethylene