Theoretical study of excited states of DNA base dimers and tetramers using optimally tuned range‐separated density functional theory

Abstract

Excited states of various DNA base dimers and tetramers including Watson-Crick H-bonding and stacking interactions have been investigated by time-dependent density functional theory using nonempirically tuned range-separated exchange (RSE) functionals. Significant improvements are found in the prediction of excitation energies and oscillator strengths, with results comparable to those of high-level coupled-cluster (CC) models (RI-CC2 and EOM-CCSD(T)). The optimally-tuned RSE functional significantly outperforms its non-tuned (default) version and widely-used B3LYP functional. Compared to those high-level CC benchmarks, the large mean absolute deviations of conventional functionals can be attributed to their inappropriate amount of exact exchange and large delocalization errors which can be greatly eliminated by tuning approach. Furthermore, the impacts of H-bonding and π-stacking interactions in various DNA dimers and tetramers are analyzed through peak shift of simulated absorption spectra as well as corresponding change of absorption intensity. The result indicates the stacking interaction in DNA tetramers mainly contributes to the hypochromicity effect. The present work provides an efficient theoretical tool for accurate prediction of optical properties and excited states of nucleobase and other biological systems. © 2015 Wiley Periodicals, Inc.

Solvent effects on the excited state characteristics of adenine–thymine base pairs

“…For example, when using the CC2 method the state of A / T charge transfer was found to be above the bright state by values of 0.6 to 0.8 eV. 3,40,75 Other DFT functionals with long range corrections, such as M05-2X and LRC-PBE0, also correctly predicted the CT state to be above the bright state by 0.5 eV 39 and 0.7 eV, 40 respectively.…”

Ionization Energies, Electron Affinities, and Polarization Energies of Organic Molecular Crystals: Quantitative Estimations from a Polarizable Continuum Model (PCM)-Tuned Range-Separated Density Functional Approach

“…17,18,23 , the molecular geometries (see Figure 1) were optimized using the PBE functional 72 and 6-31G(d,p) basis set. The optimization of the rangeseparation parameter ω was performed based on the LC-ωPBE 46, 73 functional and using the efficient "golden-ratio" algorithm, as described in our previous work 48,57 (see Supporting…”

Prediction of excited‐state properties of oligoacene crystals using polarizable continuum model‐tuned range‐separated hybrid functional approach

“…[ ] and were also included for comparison. The ω ‐tuning procedure was carried out using the home‐made “Xtune_g09” script as described elsewhere . The ground‐state geometries of oligoacene molecules were optimized using the B3LYP functional and 6‐31G(d) basis set.…”