Molecular Dynamics and Laboratory Experiments on Diffusion in Liquid Oxides

9316390里氏对熔融二氧化硅和二氧化Ge2中的扩散进行了详细的研究。将结合分子动力学(MD)模拟和实验室实验，对Si、O和Ge的自扩散的大小、激活能和激活体积进行研究。实验室实验将提供重要的基准，用来测试使用对电势的各种表示进行的MD模拟的有效性。目前使用的电势在重现液态二氧化硅的各种静态性质方面相当成功，但它们在重现动量(如原子物种的扩散系数)方面的能力尚未经过测试。验证简单氧化物的MD模拟是迈向真实的硅酸盐熔体表示的必要的第一步，并将为在原子水平上理解扩散提供基础。一个特别令人感兴趣的问题是，为什么最近所有液态二氧化硅的MD模拟都发现，硅和氧的自扩散实际上是相同的，而实验室对混合氧化物系统的实验总是发现它们明显不同？

9316390 Richter A detailed study of diffusion in molten SiO2 and GeO2 is proposed. Combined Molecular Dynamics (MD) simulations and laboratory experiments for the magnitude, activation energy, and activation volume for the self-diffusion of Si, O, and Ge will be carried out. The laboratory experiments will provide important benchmarks with which to test the validity of MD simulations carried out using a variety of representations of the pair-potentials. Presently used potentials are reasonably successful at reproducing various static properties of liquid SiO2, but they have not been tested in terms of their ability to reproduce kinetic quantities such as the diffusivity of atomic species. Validating the MD simulations for a simple oxides is a necessary first step towards the realistic representation of silicate melts, and will provide a basis for understanding diffusion at an atomistic level. A question of particular interest is why do all recent MD simulations of liquid SiO2 find that the self-diffusion of Si and O are virtually the same while laboratory experiments on mixed oxide systems always find them to be significantly different?