原子尺寸对Lennard-Jones液体玻璃转变过程中动力学不均匀性的影响

Effect of atomic size on dynamic heterogeneity of Lennard-Jones liquid in glass transition

采用分子动力学模拟技术,通过对非高斯参数α2(t)、粘度η等动力学参数的计算探究了原子尺寸对Lennard-Jones(LJ)液体在玻璃转变过程中动力学不均匀性的影响.结果表明在玻璃转变温度Tg附近,原子尺寸越小,粘度值增加越显著,且粘度随温度的变化满足Vogel–Fulcher–Tammann(VFT)方程;β弛豫阶段的非高斯参数α2(t)与时间的关系满足幂律函数,且随着原子尺寸的减小动力学不均匀性越来越明显.

The influence of atomic size on the dynamic heterogeneity of Lennard-Jones(LJ)liquid during glass transition was investigated by means of molecular dynamics simulation technology and the calculations of non-Gaussian parametersα2(t)and viscosityη.The results show that near the glass transition temperature Tg,if the atomic size is smaller,the viscosity value increases more significantly and its changes with temperature is satisfy the Vogel-Fulcher-Tammann(VFT)equation;the relation between the non-Gaussian parameterα2(t)in theβrelaxation stage and time satisfies the power law function,and the dynamic heterogeneity becomes more and more obvious with the decrease of the atomic size.