Ab Initio Study of the Dynamical Si-O Bond Breaking Event in alpha-Quartz

The Si-O bond breaking event in the alpha-quartz at the first triplet (T-1) excitation state is studied by using ab initio molecular dynamics (AIMD) and nudged elastic band calculations. A meta-stable non-bridging oxygen hole center and E' center (NBOHC-E') is observed in the AIMD which consists of a broken Si-O bond with a Si-O distance of 2.54 angstrom. By disallowing the re-bonding of the Si and O atoms, another defect configuration (III-Si/V-Si) is obtained and validated to be stable at both ground and excitation states. The NBOHC-E' is found to present on the minimal energy pathway of the initial to III-Si/V-Si transition, showing that the generating of the NBOHC-E' is an important step of the excitation induced structure defect. The energy barriers to produce the NBOHC-E' and III-Si/V-Si defects are calculated to be 1.19 and 1.28 eV, respectively. The electronic structures of the two defects are calculated by the self-consistent GW calculations and the results show a clear electron transition from the bonding orbital to the non-bonding orbital.National Natural Science Foundation of China [10744048, 11202032]; Defense Industrial Technology Development Program of China [B1520132013]SCI(E)中国科技核心期刊(ISTIC)ARTICLEjun_chen@iapcm.ac.cn103