The effect of metallic cations on the Si-O(br) bond and the Si-O(ter) bond was studied with CNDO/2 MO calculations. The characteristics of them were discussed, which were found to vary with the bonding and coordi nati...The effect of metallic cations on the Si-O(br) bond and the Si-O(ter) bond was studied with CNDO/2 MO calculations. The characteristics of them were discussed, which were found to vary with the bonding and coordi nation situation of oxygen as well as the effect of metallic cations on oxygen. The conclusions obtained may be well used in the fields of mineralogy, geochemistry, silicate materials, pyrometallurgy and so on.展开更多
The Si-O bond breaking event in the a-quartz at the first triplet （T1） excitation state is studied by using ab initio molecular dynamics （AIMD） and nudged elastic band calculations. A meta-stable non-bridging oxyg...The Si-O bond breaking event in the a-quartz at the first triplet （T1） 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 E1 center （NBOHC-E） is observed in the AIMD which consists of a broken Si-O bond with a Si-O distance of 2.54A. By disallowing the re-bonding of the Si and 0 atoms, another defect configuration （lll- 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 IlI-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 NBQHC-E＇ and Ⅲ-Si/V-Si defects are calculated to be 1.19 and 1.28eV, 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.展开更多
文摘The effect of metallic cations on the Si-O(br) bond and the Si-O(ter) bond was studied with CNDO/2 MO calculations. The characteristics of them were discussed, which were found to vary with the bonding and coordi nation situation of oxygen as well as the effect of metallic cations on oxygen. The conclusions obtained may be well used in the fields of mineralogy, geochemistry, silicate materials, pyrometallurgy and so on.
基金Supported by the National Natural Science Foundation of China under Grant Nos 10744048 and 11202032the Defense Industrial Technology Development Program of China under Grant No B1520132013
文摘The Si-O bond breaking event in the a-quartz at the first triplet （T1） 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 E1 center （NBOHC-E） is observed in the AIMD which consists of a broken Si-O bond with a Si-O distance of 2.54A. By disallowing the re-bonding of the Si and 0 atoms, another defect configuration （lll- 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 IlI-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 NBQHC-E＇ and Ⅲ-Si/V-Si defects are calculated to be 1.19 and 1.28eV, 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.
