Microscopic structure of liquid GeSe2:: The problem of concentration fluctuations over intermediate range distances

A first-principle molecular dynamics study on liquid GeSe2 yields structural properties in good agreement with detailed neutron scattering data. The short range order is accurately described by a variety of bonding configurations, in which regular tetrahedra coexist with an important fraction of homopolar bonds and threefold centers. The first sharp diffraction peak in the total structure factor, which characterizes order over intermediate range distances, is also well reproduced. However, this level of theory does not yield concentration fluctuations over such distances as observed in experiment.