Density oscillations in a model of water and other similar liquids

It is suggested that the dynamics of liquid water has a component consisting of O^{-2z} (oxygen) anions and H^{+z} (hydrogen) cations, where z is a (small) reduced effective electron charge. Such a model may apply to other similar liquids. The eigenmodes of density oscillations are derived for such a two-species ionic plasma, included the sound waves, and the dielectric function is calculated. The plasmons may contribute to the elementary excitations in a model introduced recently for the thermodynamics of liquids. It is shown that the sound anomaly in water can be understood on the basis of this model. The results are generalized to an asymmetric short-range interaction between the ionic species as well as to a multi-component plasma, and the structure factor is calculated.