title: Multiconfigurational Effects in Theoretical Resonance Raman Spectra.
abstract: We analyze resonance Raman spectra of the nucleobase uracil in the short-time approximation calculated with multiconfigurational methods. We discuss the importance of static electron correlation by means of density-matrix renormalization group self-consistent field (DMRG-SCF) calculations. Our DMRG-SCF results reveal that a minimal active orbital space that leads to a qualitatively correct description of the resonance Raman spectrum of uracil should encompass parts of the σ/σ* bonding/anti-bonding orbitals of the pyrimidine ring. We trace these findings back to the considerable entanglement between the σ/σ* bonding/anti-bonding as well as valence π/π* orbitals in the excited-state electronic structure of uracil, which indicates non-negligible non-dynamical correlation effects that are less pronounced in the electronic ground state.
authors.affiliation: ETH Zürich, Laboratorium für Physikalische Chemie, Vladimir-Prelog-Weg 2, 8093, Zürich, Switzerland.
authors.forename: Yingjin
authors.initials: Y
authors.lastname: Ma
authors.affiliation: ETH Zürich, Laboratorium für Physikalische Chemie, Vladimir-Prelog-Weg 2, 8093, Zürich, Switzerland.
authors.forename: Stefan
authors.identifier: http://orcid.org/0000-0001-9818-2372
authors.initials: S
authors.lastname: Knecht
authors.affiliation: ETH Zürich, Laboratorium für Physikalische Chemie, Vladimir-Prelog-Weg 2, 8093, Zürich, Switzerland.
authors.forename: Markus
authors.identifier: http://orcid.org/0000-0002-9508-1565
authors.initials: M
authors.lastname: Reiher
mesh_terms: D004583:Electrons; D011789:Quantum Theory; D013059:Spectrum Analysis, Raman; D014498:Uracil / Q000737:chemistry*
chemical_list: D014498:Uracil
keywords: density matrix renormalization group; multiconfigurational electronic structure methods; resonance Raman spectroscopy; short-time approximation; state-specific gradients