Quantum Mechanical Methods Related to Ionization of Nucleic Acid Bases pp. 255-284
Authors: (Emilie Cauët, Service de Chimie Quantique et Photophysique, Université Libre de Bruxelles, Bruxelles, Belgium)
Abstract: Ab initio quantum mechanical methods provide microscopic insights into DNA characteristics and are, today, essential to the full interpretation and understanding of results obtained by experimental techniques. In this chapter we summarize the contributions of modern quantum chemicalcalculations to the determination of the electronic properties of DNA bases, isolated or embedded in base clusters. In particular, the calculations discussed concern the characterization of the molecular energy levels and potential energy surfaces, which shed light on ionization and charge migration along DNA molecules. We mainly consider the estimation of key parameters, such as ionization potentials (IPs) of DNA bases, which govern the charge injection into DNA. The effects of the stacking and H-bonding DNA base interactions and the solvation of DNA on these quantities are described. We also discuss the mechanisms of charge migration over stacked DNA bases. These aspects are illustrated by a survey of the literature and by our own selected recent results.