First-Principles Calculations of the Energy and Width of the (2)A(u) Shape Resonance in p-Benzoquinone: A Gateway State for Electron Transfer.
Quinones are versatile biological electron acceptors and mobile electron carriers in redox processes. We present the first ab initio calculations of the width of the (2)A(u) shape resonance in the para-benzoquinone anion, the simplest member of the quinone family. This resonance state located at 2.5 eV above the ground state of the anion is believed to be a gateway state for electron attachment in redox processes involving quinones. We employ the equation-of-motion coupled-cluster method for electron affinity augmented by a complex-absorbing potential (CAP-EOM-EA-CCSD) to calculate the resonance position and width. The calculated width, 0.013 eV, is in excellent agreement with the width of the resonant peak in the photodetachment spectrum, thus supporting the assignment of the band to resonance excitation to the autodetaching (2)A(u) state. The methodological aspects of CAP-EOM-EA-CCSD calculations of resonances positions and widths in medium-sized molecules, such as basis set and CAP box size effects, are also discussed.
Department of Chemistry, Boston University, Boston, Massachusetts 02215, United States.
Alexander A
AA
Kunitsa
Department of Chemistry, Boston University, Boston, Massachusetts 02215, United States.
Ksenia B
KB
Bravaya
D000838:Anions / Q000737:chemistry; D016227:Benzoquinones / Q000737:chemistry*; D004579:Electron Transport; D004735:Energy Transfer; D010084:Oxidation-Reduction; D025341:Principal Component Analysis
D000838:Anions; D016227:Benzoquinones; C004532:quinone
autoionization; benzoquinone; complex absorbing potential; equation-of-motion coupled-cluster; photodetachment; resonances