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Updated: Mar 29, 2026

Excitonic Hamiltonians for Calculating Optical Absorption Spectra and Optoelectronic Properties of Molecular Aggregates and Solids
Published on: May 27, 2020
Oscillator Strength: How Does TDDFT Compare to EOM-CCSD?
Marco Caricato1, Gary W Trucks1, Michael J Frisch1
1Gaussian, Inc., 340 Quinnipiac St., Bldg. 40, Wallingford, Connecticut 06492, United States, and Department of Chemistry, Yale University, 225 Prospect St., New Haven, Connecticut 06511, United States.
Abstract:
In this work, we compare a large variety of density functionals against the equation of motion coupled cluster singles and doubles (EOM-CCSD) method for the calculation of oscillator strengths. Valence and Rydberg states are considered for a test set composed of 11 small organic molecules. In our previous work, the same systems and methods were tested against experimental results for the excitation energies. The results from this investigation confirm our previous findings, i.e., that there is a large difference between the functionals. For the oscillator strength, the average best agreement with EOM-CCSD is provided by CAM-B3LYP followed by LC-ωPBE and, to a lesser extent, B3P86 and LC-BLYP.
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