The displacement of an O atom in pure α quartz was studied via first-principles molecular dynamics. The simulations show that when an O atom in a Si-O-Si bridge was moved away from its original equilibrium position, a new stable energy minimum could be reached. Depending on the spin state and charge Q of the system, this minimum could give rise to either a threefold O (singlet ground state and Q = +1) or to an unsaturated Si atom carrying a dangling bond (triplet state). In the latter case, the hyperfine parameters associated with the 29Si dangling bond were in rather good agreement with electron paramagnetic resonance/electron nuclear double resonance experiments.

E’ Centers in α Quartz in the Absence of Oxygen Vacancies - a First-Principles Molecular-Dynamics Study. M.Boero, A.Oshiyama, P.L.Silvestrelli: Physical Review Letters, 2003, 91[20], 206401 (3pp)