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Comparison with experiment

The configuration of H in diamond found here is closely correlated with the H1 center measured by EPR experiments [81], where the H atom is speculated to be bonded to one C atom, creating a dangling bond on the neighboring C atom. Zhou at. al. [81] conclude that the H atom is $\sim$ 1.9 Å away from the unpaired electronic spin, in excellent agreement with our calculations (1.8 Å).

The present findings can be also qualitatively compared with experimental results for the positions of muonium in diamond [82]. It is now well established that the anomalous muon (Mu$^\star$) in semiconductors has small and highly anisotropic hyperfine parameters with <111> axial symmetry. Sahoo et. al. [84] suggested that in an appropriate model for Mu$^\star$, the unpaired electron should be in a delocalized orbital, comprised mainly of host atom orbitals directed towards the muon with a relatively small spin density at the muon. These conditions are fulfilled by the ET site, which is found to be close to an antibonding site. At high temperature, where the H atom jumps between ET sites around C-C bonds (see below), the axial symmetry should be recovered when averaging of the H motion is carried out. Furthermore, the dangling bond created when H is at a ET site contributes to the spin density at the proton, giving rise to the small values of the hyperfine parameters.


next up previous contents
Next: Motion of hydrogen in Up: Hydrogen in diamond Previous: A new lowest energy
David Saada
2000-06-22