title: Time-dependent density functional theory assessment of UV absorption of benzoic acid derivatives.
abstract: Benzoic acid (BA) derivatives of environmental relevance exhibit various photophysical and photochemical characteristics. Here, time-dependent density functional theory (TDDFT) is used to calculate photoexcitations of eight selected BAs and the results are compared with UV spectra determined experimentally. High-level gas-phase EOM-CCSD calculations and experimental aqueous-phase spectra were used as the references for the gas-phase and aqueous-phase TDDFT results, respectively. A cluster-continuum model was used in the aqueous-phase calculations. Among the 15 exchange-correlation (XC) functionals assessed, five functionals, including the meta-GGA hybrid M06-2X, double hybrid B2PLYPD, and range-separated functionals CAM-B3LYP, ωB97XD, and LC-ωPBE, were found to be in excellent agreement with the EOM-CCSD gas-phase calculations. These functionals furnished excitation energies consistent with the pH dependence of the experimental spectra with a standard deviation (STDEV) of ∼0.20 eV. A molecular orbital analysis revealed a πσ* feature of the low-lying transitions of the BAs. The CAM-B3LYP functional showed the best overall performance and therefore shows promise for TDDFT calculations of processes involving photoexcitations of benzoic acid derivatives.
authors.affiliation: UT/ORNL Center for Molecular Biophysics, Oak Ridge National Laboratory, Tennessee 37831, United States.
authors.forename: Hao-Bo
authors.initials: HB
authors.lastname: Guo
authors.forename: Feng
authors.initials: F
authors.lastname: He
authors.forename: Baohua
authors.initials: B
authors.lastname: Gu
authors.forename: Liyuan
authors.initials: L
authors.lastname: Liang
authors.forename: Jeremy C
authors.initials: JC
authors.lastname: Smith
mesh_terms: D001565:Benzoates / Q000737:chemistry*; D015394:Molecular Structure; D011789:Quantum Theory; D013056:Spectrophotometry, Ultraviolet; D013997:Time Factors; D014466:Ultraviolet Rays
chemical_list: D001565:Benzoates