First Principles Theory Of Hyperfine Interactions In Guanine Nucleobase

Abstract

The electronic structure and the muonium hyperfine interactions in guanine nucleobase were investigated using the unrestricted Hartree-Fock cluster procedure in combination with the 6-311G(d,p) basis set. The effect of muonium on the planar shape of the guanine nucleobase varies depending on the trapping sites. Non-planar characteristic of guanine base was observed when muonium is trapped at C4, C5, or C6 atoms. The guanine base retains its planar geometry when muonium is present at C2, C8, N3, N7, or O6 atoms. The muonium hyperfine coupling constant at the different sites ranges from -31.3 MHz to 366.3 MHz. Based on the minimum total energy consideration, C8 is the most stable trapping site. The calculated value of the muonium Fermi contact coupling constant in the guanine nucleobase is in good agreement with the µSR data. This study provides an excellent overall understanding of the effect of muonium addition to the various trapping sites in the guanine base and the associated hyperfine properties.