Vacancy associated model for anomalous muonium in diamond, silicon and germanium

Through first-principles investigations on a number of models for anomalous muonium in diamond using the Unrestricted Hartree-Fock Cluster procedure, it is demonstrated that a muonium trapped near a double-positively charged vacancy is the most viable model for this center. This model is shown to successfully explain all the observed features of the hyperfine tensors A^{{rightwards paired arrows}} in diamond, silicon and germanium, namely, oblateness, opposite signs of A_{{box drawings light vertical}} and A_{{drawings box light vertical and horizontal}} in diamond and same signs for silicon and germanium, the trend in the strengths of the hyperfine tensors from diamond to germanium and the negative sign for A_{{drawings box light vertical and horizontal}} in diamond.