Applicability of optimal functional tuning in density functional calculations of ionization potentials and electron affinities of adenine–thymine nucleobase pairs and clusters

Abstract

The intrinsic properties of DNA and RNA nucleic acid bases (NABs) such as ionization potentials (IPs) and electron affinities (EAs) are crucial to reveal various biochemical mechanisms. Successful application of density functional theory (DFT) using nonempirically tuned long-range corrected (LC) functionals for calculation of vertical ionization potentials (VIPs) and electron affinities (VEAs) of various adenine-thymine (AT) nucleobase pairs and clusters is demonstrated. We employ a tuning method by applying an asymptotically correct exchange-correlation potential adjusted to give frontier orbital energies (-εHOMO and -εLUMO) representing IPs and EAs and assess the quality of prediction which is comparable to high-level EOM-IP-CCSD/CCSD methods. The delocalization error calculated using different DFT functionals is quantified by calculations using fractional electron numbers. The cooperative effect of H-bonding and π-stacking on the IPs of AT clusters, as well as the reactivity parameters (global hardness and electrophilicity), is quantitatively characterized using the tuned LC functionals. The present work aims at providing a reliable and efficient theoretical tool for the prediction of the related electron donor and acceptor abilities of the NAB systems.

Density-functional errors in ionization potential with increasing system size

“…For small molecules, ω tuning has been reported to improve prediction of ionization potentials, 29,34,35,38,45 polarizabilities, 48 hyperpolarizabilities, 43,44 and fundamental gaps, 34,39,40,42,46 relative to LRC functionals with default ω values. Furthermore, FIG.…”

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

“…Créspo‐Hernandez et al have shown the key role of stacking interaction in the control of the excited‐state dynamics in an AT complex . Therefore, DNA pairs and especially larger clusters, which combine hydrogen(H‐) bonding and π ‐stacking interactions, are relevant prototypical systems to be studied since they can be seen as the basic building blocks of a realistic DNA duplex . From a theoretical perspective care must be taken, however, in choosing an appropriate level of theory that is capable of providing both efficient and accurate prediction of the excited‐state properties of the DNA building blocks …”

“…can benefit properties that depend on not only HOMO energy but also on LUMO energy of N ‐electron system. Our earlier work has demonstrated that vertical ionization potentials of various adenine‐thymine pairs and clusters can be well described using this “tuning” method . Moore et al have demonstrated that the optimal tuning approach allows to obtain accurate excitation energies without degrading the description of band shapes for a set of small organic molecules.…”

“…[2] Therefore, DNA pairs and especially larger clusters, which combine hydrogen(H-) bonding and pstacking interactions, are relevant prototypical systems to be studied since they can be seen as the basic building blocks of a realistic DNA duplex. [18] From a theoretical perspective care must be taken, however, in choosing an appropriate level of theory that is capable of providing both efficient and accurate prediction of the excited-state properties of the DNA building blocks. [19] Various computational approaches from low to high levels of theory have been performed to describe the excitation spectrum and excited-state relaxation of NABs.…”

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

“…50,51 This tuning procedure is based on the IP (ionization potential)-theorem, which states that the negative HOMO energy (−ε H ) in exact Kohn-Sham DFT is equal to the vertical IE, that is, the difference in total energy between the neutral and cationic systems for a fixed geometry. 52 It has been demonstrated that the tuning concept yields reliable descriptions of both ground-state properties 35,[52][53][54][55] and excited-state properties 9, 56-58 of organic molecules and polymer chains. 48 The IP-tuning procedure has also been shown to predict frontier orbital energies of molecules with an accuracy comparable to the GW approximation at lower computational costs.…”