Theoretical Exploration of ~(29)Si Hyperfine and Superhyperfine Parameters of E' Centers as a Measure of Range-II Order in a-SiO_2

摘要

We present an ab initio molecular orbital study of the Griscom-Cook postulate that, in aSiO_2, E_gamma' Centers will spontaneously distort to minimize the number of second-nearest-neighbor silicon atoms in back-bonded positions. Our calculations do not support this assertion. Rather, we found that back-bonded, secondnearest-neighbors are preferred. We discuss the physical mechanism for this observation. We also discuss the physical implications of our results. We also discuss briefly our ab initio values for the ~(29)Si hyperfine and superhyperfine interactions. These are in good agreement with experiment.