THE VORONOI POLYHEDRA AS TOOLS FOR STRUCTURE DETERMINATION IN SIMPLE DISORDERED-SYSTEMS

The structure of some simple fluids is analyzed through the Voronoi te ssellation of the configurations generated by computer simulation. Spe cial emphasis is put on the investigation of disordering, ix.e., the d eviation from solid-state properties. The models studied include a sim ple Lennard-Jones (LJ) liquid, two quenched states obtained from the l iquid, and a system made of noninteracting particles (the ideal gas), while a state point corresponding to the LJ solid phase is used as ref erence. To perform the Voronoi construction, an algorithm specially su ited for disordered systems is presented. The arrangement of particles has been studied through the geometrical features of their Voronoi po lyhedra (VP). It is shown that two parameters can give a description o f the VP in such a way that the disordering of the system is clearly m anifested. One is the volume distribution coefficient of skewness, and the other is the shape of the VP as described by the convex bodies no nsphericity factor. In particular, the clusters present in a rapidly q uenched liquid are easily revealed in this way.