Microstructure of glass-forming amorphous solids has been investigated by molecular dynamics (MD) simulation coupled with Voronoi-Delaunay (VD) tessellation. The NTP ensemble MD models are constructed from Ar atoms interacting via Lennard-Jones potential and amorphous solids have been obtained by quench from an equilibrium liquid state. By utilizing the VD tessellation for the quenching process, we calculated statistical variables (expected value V_E, variance σ, deviation σ^<1/2>, skewness, probability density function f_i) and Shannon's information entropy S about the volume of Voronoi polyhedra V_i as a function of temperature T. From T-V_E relation, glass transition temperature T_g is approximated to be 48K which is close to 1/2 of melting point T_m. The variance and deviation showed monotonic decreasing with temperature and a finite inflection in T-S relation has been identified around T_g. Local density calculated from spatial distribution of V_i starts to show notable fluctuation below T_g suggesting that non-erogodic sampling in configurational space becomes significant as expected from mode coupling theory.
