Molecular dynamics simulation and statistical analysis for glass transition in a Lennard-Jones system

Microstructure of glassy solids have been investigated by molecular dynamics (MD) simulation coupled with a Voronoi-Delaunay (VD) tessellation. NTP ensemble MD models are constructed from Ar atoms interacting via Lennard-Jones potential and glassy solids have been obtained by rapid quenches from an equilibrium liquid state. By utilizing the VD tessellation for a quenching process, we calculated statistical variables (expected value V_E, variance σ², deviation σ, skewness γ₁, kurtosis γ₂, probability density distribution function. f _i and Shannon's information entropy S) from volumes of Voronoi polyhedra V_i. The V_E-T and S-T relationships show notable inflections around 55 K showing a glass transition phenomenon. During the quench process, f_i continuously approaches to Gaussian form while γ₁ and γ₂ show significant inflections below T_g indicating that microstructure and local density fluctuation of the glassy solid suddenly freeze around T_g.