Voronoi Structural Evolution of Bulk Silicon upon Melting

The Voronoi structural evolution of silicon upon melting is investigated using a molecular dynamics simulation. At temperatures below the melting point, the solid state system is identified to have a four-fold coordination structure 〈4,0,0,0〉. As the temperature increases, the five−fold coordination 〈2,3,0,0〉 and six−fold coordination structures 〈2,2,2,0〉 and 〈0,6,0,0〉 are observed. This is explained in terms of increasing atomic displacement due to thermal motion and the trapping of the moving atoms by others. At temperatures above the melting point, nearly all of the four-fold coordination structures grows into multiple-fold coordination ones.