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Modelling the surface of amorphous dehydroxylated silica: the influence of the potential on the nature and density of defects†
New Journal of Chemistry ( IF 2.7 ) Pub Date : 2017-12-13 00:00:00 , DOI: 10.1039/c7nj03922k
Stéphanie Halbert 1, 2, 3, 4, 5 , Simona Ispas 3, 4, 6, 7, 8 , Christophe Raynaud 1, 2, 3, 4, 5 , Odile Eisenstein 1, 2, 3, 4, 5
Affiliation  

Molecular dynamics (MD) calculations using two effective pair potentials BKS and CHIK have been carried out to represent the structures of the amorphous dehydroxylated silica surface in liquid (3400 and 2500 K) and glassy (1000 and 300 K) states. Previous studies have shown that CHIK performs better to represent the properties of bulk silica and this may result from the different values of the Si–O and O–O parameters, as well as from an additional Si⋯Si short range interaction term. The two potentials show similar trends in the change of structures upon going from the internal to the surface parts of the samples. However, the additional flexibility, likely due to the presence of the Si⋯Si short range interaction, relative to BKS, results in a surface which has overall more defects like in particular small 2-membered rings (SiO2)2 and dangling Si–O bonds. This cumulated density of defects corresponds qualitatively to the density of functionalized Si–OH obtained experimentally. This study shows that CHIK gives a good representation of the silica surface.

中文翻译:

模拟非晶态脱羟基二氧化硅的表面:电势对缺陷的性质和密度的影响

已经进行了使用两个有效的对势BKS和CHIK的分子动力学(MD)计算,以代表液态(3400和2500 K)和玻璃态(1000和300 K)的非晶态脱羟基二氧化硅表面的结构。先前的研究表明,CHIK可以更好地表示块状二氧化硅的性能,这可能是由于Si-O和O-O参数的值不同以及附加的Si⋯Si短程相互作用项引起的。从样品的内部到表面部分,这两个电位在结构变化中显示出相似的趋势。但是,相对于BKS,可能由于存在Si⋯Si短程相互作用而产生的额外柔韧性导致表面总体上具有更多缺陷,例如特别是小的2元环(SiO2 2和悬空的Si–O键。累积的缺陷密度在质量上与实验获得的官能化Si-OH的密度相对应。这项研究表明,CHIK可以很好地表示二氧化硅表面。
更新日期:2017-12-13
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