Mode contributions of different collective excitations to the density-density time correlation function in liquid lead are studied within the nine-variable approach of generalized collective modes. It is shown, that a kinetic relaxing mode, caused by slow density fluctuations, defines almost completely the shape of density-density time correlation function for wave numbers close to the main peak position of the static structure factor. The physical meaning of this mode is discussed.

• Received 4 December 2000

DOI:https://doi.org/10.1103/PhysRevE.64.032202