Discrete approach to incoherent excitations in conductors
  Keeping the discretness of the reciprocal space we calculate the spectrum of incoherent electron-hole excitations in the conducting Fermi liquids. The metod is illustrated on the well-known jellium model within the random phase approximation. It also leads to the formulation os a sum rule from which we get the details os dispersion curve for the collective plasmon mode. The notion of time averaging in the discrete approach is briefly recalled. 
P. Zupanovic, A. Bjelis, Z. Agic