2018/10/30 by Pierre-François Loos, Pierre‐François Loos, Denis Jacquemin
Chemistry · Mathematics · Physics and Astronomy · #Advanced Chemical Physics Studies #Algorithm #Atomic physics #Basis set #Chemistry #Computation #Computational chemistry #Computational physics #Computer science #Density functional theory #Error bar #Excitation #Excited state #Matching (statistics) #Mathematics #Photochemistry and Electron Transfer Studies #Physics #Quantum mechanics #Singlet state #Spectroscopy and Laser Applications #Wave function #physics.chem-ph #physics.comp-ph
paper · pdf · doi:10.1021/acs.jctc.8b01103
published as J. Chem. Theory Comput. 15, 2481 (2019) · 11 pages, 5 figures
arxiv created 2018/10/30 · openalex publication_date 2019/02/25 · arxiv updated 2019/05/06 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/05
Using a series of increasingly refined wave function methods able to tackle electronic excited states, namely ADC(2), CC2, CCSD, CCSDR(3), and CC3, we investigate the interplay between geometries and 0–0 energies. We show that, due to a strong and nearly systematic error cancelation between the vertical transition and geometrical reorganization energies, CC2 and CCSD structures can be used to obtain chemically accurate 0–0 energies, though the underlying geometries are rather far from the reference ones and would deliver significant errors for several chemical and physical properties. This indicates that obtaining 0–0 energies matching experiment does not demonstrate the quality of the underlying geometrical parameters. By computing CC3 total energies on CCSD structures, we model a large set of compounds (including radicals) and electronic transitions (including singlet–triplet excitations) and successfully reach chemical accuracy in a near systematic way. Indeed, for this particular set, we obtain a mean absolute error as small as 0.032 eV, chemical accuracy (error smaller than 1 kcal·mol –1 or 0.043 eV) being obtained in 80% of the cases. In only three cases out of more than 100 examples, the error exceeds 0.15 eV which is of the order of the typical error provided by TD-DFT or second-order wave function methods for 0–0 energies. The present composite approach seems therefore effective, at least for low-lying states, despite the fact that the geometries may not be considered as very accurate.