  We present a study of the structural properties of (x)Na$_2$S-(1-x)GeS$_2$
glasses through DFT-based molecular dynamics simulations, at different sodium
concentrations ($0<x<0.5$). We computed the radial pair correlation functions
as well as the total and partial structure factors. We also analyzed the
evolution of the corner- and edge-sharing intertetrahedral links with the
sodium concentration and show that the sodium ions exclusively destroy the
former. With the increase of the sodium concentration the ``standard'' FSDP
disappears and a new pre-peak appears in the structure factor which can be
traced back in the Na-Na partial structure factor. This self organization of
the sodium ions is coherent with Na-rich zones that we find at high modifier
concentration.
