Analysis of the Distribution and Influencing Factors of Diffusion Coefficient Model Parameters Based on Molecular Dynamics Simulations

The establishment of mathematical models to predict thediffusioncoefficients of gas and liquid systems have important theoreticalsignificance and practical value. In this work, based on the previouslyproposed diffusion coefficient model D (LV), the distribution and influencing factors of the model parameterscharacteristic length (L) and diffusion velocity(V) were further investigated using molecular dynamicssimulations. The statistical analysis of L and V for 10 gas systems and 10 liquid systems was presentedin the paper. New distribution functions were established to describethe probability distributions of molecular motion L and V. The mean values of the correlation coefficientswere 0.98 and 0.99, respectively. Meanwhile, the effects of molecularmolar mass and system temperature on the molecular diffusion coefficientswere discussed. The results show that the effect of molecular molarmass on the diffusion coefficient mainly affects the molecular motion L, and the effect of system temperature on the diffusioncoefficient mainly affects V. For the gas system,the average relative deviation of D (LV) and D (MSD) is 10.73% and that of D (LV) and experimental value is 12.63%; for the solutionsystem, the average relative deviation of D (LV) and D (MSD) is 12.93% and that of D (LV) and experimental value is 18.86%, which indicatesthe accuracy of the new model results. The new model reveals the potentialmechanism of molecular motion and provides a theoretical basis forfurther study of the diffusion process.