Résumé
A numerical Voronoï tessellation is used to investigate the local order in two classes of model glassy systems: (i) random close packings of 8192 hard spheres with increasing volume fractions, c, built with an efficient algorithm, (ii) supercooled liquid and glass samples of 1000 atoms at different temperatures, T, obtained after a quench from the liquid state, using classical micro-canonical molecular dynamics (MD) with a simple soft-sphere potential. As a general result, when increasing c in case (i) or when decreasing T in case (ii), the ideal icosahedral order, with five-fold symmetry, appears as an extrapolated situation which cannot be realized due to geometrical frustration.