First Principles Study of Nuclear Quadrupole Interactions in Single and Double Chain DNA and Solid Nucleobases

Nuclear Quadrupole Interactions (NQI) of $^{17}$O, $^{14}$N and $^{2}$H nuclei have been studied for free nucleobases and nucleobases in single strand and double strand DNA and in solid state. Our first-principles investigations were carried out using the Gaussian 2003 set of programs to implement the Hartree-Fock procedure combined with many-body effects included using many-body perturbation theory. As expected for NQI in general, many-body effects are found to be small. Results will be presented for the quadrupole coupling constants (e$^{2}$qQ) and asymmetry parameters ($\eta)$ for the nucleobases in the various environments. Trends in e$^{2}$qQ and $\eta $ in the different environments will be discussed. In the case of the solid nucleobases, comparisons will be made with available experimental data [1] for $^{17}$O nuclei.\\[3pt] [1] Gang Wu et al., J. Am. Chem. Soc. 124, 1768 (2002)