初始碳烟颗粒形成的反应分子动力学模拟

A ReaxFF Molecular Dynamics Simulation of the Formation of Nascent Soot Particles

本文采用ReaxFF反应分子动力学模拟的方法研究了温度对PAH生成初始碳烟颗粒的路径的影响。低温时(400 K),PAH单体分子通过物理成核的方式形成初始碳烟颗粒。中等温度时(1600 K),PAH只能形成二聚物或三聚物,无法发生从气相单体到固相碳烟颗粒的转变。当温度升高到2500 K,PAH通过化学成核形成碳烟颗粒,PAH分子首先分解形成碳链分子,碳链分子相互链接进一步形成富勒烯结构的碳烟颗粒。

Effects from temperature on the formation mechanisms of nascent soot particle from PAH monomers are studied using ReaxFF molecular dynamics simulations. At low temperatures （400 K）, growth of soot particles from PAH monomers is through physical nucleation mechanism. At moderate temperatures （1600 K）, PAH can only grow into dimer or trimer, which can hardly experience the phase transformation from gas phase monomers to solid phase soot particles. When the temperature increases to 2500 K, formation of soot particles is through chemical nucleation mechanism. Broken of C-H and C-C bonds leads to the formation of C-chains. Then these C-chains connect to form fullerene-like structures.