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The Si-0 bond breaking event in the α-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 A.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.
The Si-0 bond breaking event in the α-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 The center (NBOHC-E ’) is observed in the AIMD which consists of a broken Si-O bond with a Si-O distance of 2.54 A. By disallowing the re-bonding of the Si and O atoms, another defect configuration -Si / V-Si) is obtained and validated to be stable at both ground and excitation states. 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 are calculated to be 1.19 and 1.28 eV, respectively. 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