title: Vertical transition energies vs. absorption maxima: illustration with the UV absorption spectrum of ethylene.
abstract: We revisit the validity of making a direct comparison between measured absorption maxima and computed vertical transition energies within 0.1 eV to calibrate an excited-state level of theory. This is illustrated on the UV absorption spectrum of ethylene for which the usual experimental values of 7.66 eV (V←N) and 7.11 eV (R(3s)←N) cannot be compared directly to the results of electronic structure calculations for two very different reasons. After validation of our level of theory against experimental data, a new experimental reference of 7.28 eV is suggested for benchmarking the Rydberg state, and the often-cited average transition energy (7.80 eV) is confirmed as a safer estimate for the valence state.
authors.affiliation: Institut Charles Gerhardt Montpellier, Université Montpellier 2, CC 15001, Place Eugène Bataillon, 34095 Montpellier, France. Electronic address: benjamin.lasorne@univ-montp2.fr.
authors.forename: Benjamin
authors.initials: B
authors.lastname: Lasorne
authors.forename: Joaquim
authors.initials: J
authors.lastname: Jornet-Somoza
authors.forename: Hans-Dieter
authors.initials: HD
authors.lastname: Meyer
authors.forename: David
authors.initials: D
authors.lastname: Lauvergnat
authors.forename: Michael A
authors.initials: MA
authors.lastname: Robb
authors.forename: Fabien
authors.initials: F
authors.lastname: Gatti
mesh_terms: D000465:Algorithms; D003198:Computer Simulation; D004583:Electrons; D005030:Ethylenes / Q000737:chemistry*; D008956:Models, Chemical; D011789:Quantum Theory; D013056:Spectrophotometry, Ultraviolet
chemical_list: D005030:Ethylenes; C036216:ethylene
keywords: Absorption maximum; Ethylene; Excited-state quantum chemistry; Franck–Condon factors; UV–visible spectroscopy; Vertical transition energy