Tracking the effects of rigidity percolation down to the liquid state: relaxational dynamics of binary chalcogen melts.

The stochastic dynamics of binary liquids with formula AxB1-x, x=0-0.4 is investigated by neutron spin-echo spectroscopy. These compositions comprise samples of varying chemical connectivity, ranging from twofold-coordinated liquid Se to higher average coordinated As2S3. The parameters giving the temperature dependence of the relaxation patterns show a quasilinear dependence on the average coordination number. The results thus extend the validity of the rigidity concept into the normal liquid state and emphasize the role played by the fine details of atomic bonding on the dynamics at 10 ps-1 ns scales.