2018/02/23 by Alan D. Chien, Adam A. Holmes, Adam Holmes +5 · 6 citations
Chemistry · Earth and Planetary Sciences · Physics and Astronomy · #Advanced Chemical Physics Studies #Atmospheric Ozone and Climate #Atomic physics #Chemistry #Computational chemistry #Configuration interaction #Degenerate energy levels #Excitation #Excited state #Full configuration interaction #Methylene #Molecular physics #Organic chemistry #Ozone #Physics #Quantum mechanics #Ring (chemistry) #Spectroscopy and Laser Applications #physics.chem-ph #physics.comp-ph
paper · pdf · doi:10.1021/acs.jpca.8b01554
openalex publication_date 2018/02/23 · arxiv created 2018/03/15 · arxiv updated 2018/03/19 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/05
The electronically excited states of methylene (CH 2 ), ethylene (C 2 H 4 ), butadiene (C 4 H 6 ), hexatriene (C 6 H 8 ), and ozone (O 3 ) have long proven challenging due to their complex mixtures of static and dynamic correlations. The semistochastic heat-bath configuration interaction (SHCI) algorithm, which efficiently and systematically approaches the full configuration interaction (FCI) limit, is used to provide close approximations to the FCI energies in these systems. This article presents the largest FCI-level calculation to date on hexatriene, using a polarized double-ζ basis (ANO-L-pVDZ), which gives rise to a Hilbert space containing more than 10 38 determinants. These calculations give vertical excitation energies of 5.58 and 5.59 eV, respectively, for the 2 1 A g and 1 1 B u states, showing that they are nearly degenerate. The same excitation energies in butadiene/ANO-L-pVDZ were found to be 6.58 and 6.45 eV. In addition to these benchmarks, our calculations strongly support the presence of a previously hypothesized ring-minimum species of ozone that lies 1.3 eV higher than the open-ring-minimum energy structure and is separated from it by a barrier of 1.11 eV.