Muon-bonding site search in MgO: possible implications for earthquake-precursor detection

A computational model is used to study and locate the muon-bonding sites in MgO. Likely, the positive muon localizes in a vacant oxygen tetrahedron. This is similar to what has been observed in other well-known oxides like Fe$_{\mathrm{2}}$O$_{\mathrm{3}}$. Potentials are given by a Morse function (describing the muon-oxygen bonding) and Coulombic interactions between the muon and the four O[-2] ions. We plan to extend our work to a larger cluster, extending over a couple of lattice cells (and later over the whole lattice). These investigations are performed in support of Muon-Spin-Resonance ($\mu $SR) MgO {\&} MnO studies, [1] for which $\mu $SR signals have been observed. For MnO, only one signal has been observed, as expected. In MgO, an additional sharp signal has been seen, suggesting the existence of extended O[-1] states.[1] The latter can be seen as O[-1] earthquake-like precursor effects. [2] 1] C Boekema \textit{et al,} APS March meeting (2016). 2] FT Freund, Nat Hazards Earth Sys Sci \textbf{7} (2007) 1; FT Freund \textit{et al,} Phys Chem Earth \textbf{31} (2006) 389.