二氧化硅表面稠密的二氧化碳分子动力学模拟

采用分子动力学的方法研究二氧化硅表面二氧化碳的结构和扩散性质。二氧化碳在二氧化硅固体表面形成高密度层;而在远离固体表面处,流体的密度分布类似于宏观二氧化碳,取向分布比较随机。受固体表面的影响,二氧化碳的C-C径向分布函数第一峰的高度比宏观二氧化碳高。二氧化碳的密度分布和自由能分布有一明显的"镜面对称"的结构,高密度区域对应自由能的深阱。二氧化硅中的二氧化碳的自扩散行为是各向异性的,z方向的扩散由于固体面的作用明显受阻。由取向相关函数积分得到的二氧化硅表面流体的取向相关时间比宏观流体大的多,二氧化碳分子在固体表面再定位比较缓慢。

Molecular dynamics simulation of dense carbon dioxide fluid on silica surfaces

To study the structure property and diffusion behaviours,molecular dynamics simulations of dense carbon dioxide on the a- morphous silica surfaces have been carried out.The interface density profiles,adsorption free energy profiles,surface orientation order parameters the radial distribution functions for the CO_2 molecules have been presented in order to study the effect of the amorphous sur- faces on the microscopic interface structure properties of the CO_2 molecules.The translational diffusion and orientation rotation at silica surfaces have also been investigated.It was observed that there is a marked hindrance in the translational diffusion and orientation ra- tion for the CO_2 molecules near the amorphous silica surfaces.