Relaxation of the Off-Centered H^- ion at E'₄ Defect Center in α-Quartz

Abstract
The cluster calculations of the configuration with energy minima for E'₄ defect center indicate a double-well potential energy profile for off-centered displacement of the H^- ion substituting for the oxygen at the E'₄ center in α-quartz. Pseudo Jahn-Teller effect formalism is applied to interpret the cluster calculated data. The Schrödinger equation with pseudo Jahn-Teller potential energy is numerically solved. The eigenvalue spectrum and corresponding wave functions of these lowered symmetry centers are found. Applying a modified reaction rate method the relaxation times of H^- ion are computed. The acoustic losses Q^-1 are computed and compared to experimental data. The specific profile of the adiabatic potential energy, the calculated energy spectrum and the corresponding relaxation times denote that H^- ion is a mixed tunneling-relaxation system. The presented theoretical results may be useful in forecasting the radiation response of α-quartz.