First-principles Study of Muon and Muonium in A- and B-form DNA

We have carried out a systematic first-principles study of muon ($\mu^+$) and muonium ($\mu^+ e^-$) adducts in A--form and B--form DNA. All potential trapping sites in the four bases ADE, CYT, GUA, and THY were considered. Our results indicate that the difference in structural geometry between A-- and B--form DNA can lead to substantial deviations in the hyperfine fields at the $\mu^+$ sites. This could have important implications for the interpretation of Muon Spin Relaxation measurements that have shown evidence for an enhanced electron mobility in A--form DNA, but implicitly assume a negligible difference in the magnitude of the hyperfine fields at the trapped $\mu^+$ site between A-- and B--form DNA.