title: E' centers in alpha quartz in the absence of oxygen vacancies: a first-principles molecular-dynamics study.
abstract: The displacement of an oxygen atom in pure alpha quartz is studied via first-principles molecular dynamics. The simulations show that when an O atom in a Si-O-Si bridge is moved away from its original equilibrium position, a new stable energy minimum can be reached. Depending on the spin state and charge Q of the system, this minimum can give rise to either a threefold oxygen (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 are in rather good agreement with electron paramagnetic resonance/electron nuclear double resonance experiments.
authors.affiliation: Institute of Physics, University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki 305-8571, Japan.
authors.forename: Mauro
authors.initials: M
authors.lastname: Boero
authors.forename: Atsushi
authors.initials: A
authors.lastname: Oshiyama
authors.forename: Pier Luigi
authors.initials: PL
authors.lastname: Silvestrelli