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CALCULATION OF ELECTRON AFFINITIES OF POLYCYCLIC AROMATIC HYDROCARBONS AND SOVATION ENERGIES OF THEIR ANIONS
Citation:
Betowski, L D., M. Enlow, L A. Riddick, AND D. H. Aue. CALCULATION OF ELECTRON AFFINITIES OF POLYCYCLIC AROMATIC HYDROCARBONS AND SOVATION ENERGIES OF THEIR ANIONS. JOURNAL OF PHYSICAL CHEMISTRY A. American Chemical Society, Washington, DC, 110(47):12927-12946, (2006).
Impact/Purpose:
Provide state-of-the-science sampling, analysis, separation, and detection methods to allow rapid, accurate field and laboratory analyses of contaminated soils, sediments, biota, and groundwater to support Superfund clean-up decisions. Apply state-of-the-science methods in chemical analysis and data interpretation (e.g., mass spectral interpretation) to actual problems of OSWER, the Regions, and the States, in cooperation with the Las Vegas Technical Support Center as well as by direct contacts with Regional and State employees. Provide technical advice and guidance to OSWER using the environmental chemistry expertise (e.g., mass spectrometry, analytical methods development, clean-up methodology, inorganics, organometallics, volatile organics, non-volatile organics, semi-volatile organics, separation technologies, etc.) found within the branch.
Technical research support for various projects initiated either by Regions/Program Offices or ECB scientists. While these efforts will support the Regions and Program Offices, they cannot be predicted or planned in advance, and may serve multiple duty (e.g., solve real-world problems, serve to ground-truth analytical approaches that ECB is developing, transfer new technology). Many of the activities in this task support requests involving enforcement decisions and therefore are categorized as "environmental forensics".
Description:
Electron affinities (EAs) and free energies for electron attachment have been calculated for 42 polynuclear aromatic hydrocarbons and related molecules by a variety of theoretical models, including Koopmans' theorem methods and the L1E method from differences in energy between the neutral hydrocarbon and radical anion. Standard errors from linear regressions between theoretical and experimental free energies are about 0.09 eV for the L1E method using density functional theory (DFT) methods, B3L YP/6-311 G(d,p) and B3L YP/6- 31 +G(d,p). With the Hartree-Fock and MP2 methods, spin contamination is a problem, and Electron affinities (EAs) and free energies for electron attachment have been calculated for 42 polynuclear aromatic hydrocarbons and related molecules by a variety of theoretical models, including Koopmans' theorem methods and the L1E method from differences in energy between the neutral hydrocarbon and radical anion. Standard errors from linear regressions between theoretical and experimental free energies are about 0.09 eV for the L1E method using density functional theory (DFT) methods, B3L YP/6-311 G(d,p) and B3L YP/6- 31 +G(d,p). With the Hartree-Fock and MP2 methods, spin contamination is a problem, and larger standard errors of 0.14 eV or more are found, even with correction for the quartet spin state contamination by the PMP2 spin-projection methods.