Localized-orbital approach to the electronic structure of anomalous muonium in diamond

Characteristics of the electronic structure of anomalous muonium in diamond are investigated based on the relaxed-bond-centered (RBC) model by use of a self-consistent Green's-function method within the local-spin-density-functional formalism. A minimal basis set of well-contracted localized orbitals determined from first principles is used. For the case of 42% stretched C-C bond length, calculated values of -137 and 400 MHz for the Fermi-contact and dipolar hyperfine parameters, respectively, give good agreement with the experimental values of -206 and 374 MHz, strongly supporting the RBC model. A simple interpretation is also given of the mechanism for the negative Fermi-contact hyperfine parameter.