Time-dependent density functional study on the electronic excitation energies of polycyclic aromatic hydrocarbon radical cations of naphthalene, anthracene, pyrene, and perylene
- Department of Chemistry, University of California, and Chemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720 (United States)
- NASA Ames Research Center, Moffett Field, California 94035 (United States)
Time-dependent density functional theory (TDDFT) and its modification, the Tamm{endash}Dancoff approximation to TDDFT, are employed to calculate the electronic excitation energies and oscillator strengths for a series of polycyclic aromatic hydrocarbon radical cations. For the radical cations of naphthalene and anthracene, TDDFT using the Becke{endash}Lee{endash}Yang{endash}Parr functional and the 6-31G{sup {asterisk}}{sup {asterisk}} basis set provides the excitation energies that are roughly within 0.3 eV of the experimental data. The assignments of the electron transitions proposed by TDDFT accord with the previous assignments made by accurate {ital ab initio} calculations, except that TDDFT indicates the existence of a few additional transitions of {pi}{sup {asterisk}}{l_arrow}{sigma} character among the several low-lying transitions. The calculated energies for these {pi}{sup {asterisk}}{l_arrow}{sigma} transitions are found to be consistent with the onset of a {sigma} electron ionization manifold in the photoelectron spectra. For the pyrene radical cation, TDDFT supports the previous assignments made by semiempirical calculations, whereas for the perylene radical cation, TDDFT suggests the energy ordering of the three lowest-lying excited states be changed from those of the semiempirical results. {copyright} {ital 1999 American Institute of Physics.}
- OSTI ID:
- 687997
- Journal Information:
- Journal of Chemical Physics, Journal Name: Journal of Chemical Physics Journal Issue: 19 Vol. 111; ISSN JCPSA6; ISSN 0021-9606
- Country of Publication:
- United States
- Language:
- English
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