First principles investigation of the intermediate range order in disordered materials:: the case of SiSe2

The structural properties of liquid SiSe2 are studied by using first-principles molecular dynamics simulations. A comparative analysis involving liquid GeSe2 is carried out by focusing on partial pair correlation functions and coordination numbers. Both systems are characterized by intermediate range order. However, chemical order is more enhanced in liquid SiSe2 than in liquid GeSe2, leading to a larger percentage of AX(4) tetrahedra and a smaller number of homopolar bonds. (C) 2002 Elsevier Science B.V. All rights reserved.